Placental inflammation by HMGB1 activation of TLR4 at the syncytium

Association of maternal blood high-mobility group box 1 levels and adverse pregnancy outcomes: A systematic review and meta-analysis

Conflicting findings have emerged regarding the levels of high mobility group box 1 (HMGB1) in individuals experiencing adverse pregnancy outcomes. Here we conducted a meta-analysis to assess the association between maternal blood HMGB1 levels and adverse pregnancy outcomes. Utilizing databases such as PubMed, Cochrane Central Register of Controlled Trials, Web of Science, Embase and China National Knowledge Infrastructure (CNKI), a systematic literature search was conducted in January 2024. Eligible literature was screened according to inclusion and exclusion criteria. Quality assessment was evaluated using the Newcastle-Ottawa Scale (NOS). The extracted data were analyzed using Review Manager 5.4 and STATA 12.0 software. 21 observational studies with a total of 2471 participants were included in this meta-analysis. Significantly higher peripheral blood levels of HMGB1 were associated with preeclampsia (PE) (SMD=1.34; 95% CI: 0.72-1.95; P < 0.0001) and gestational diabetes mellitus (GDM) (SMD=1.20; 95% CI: 0.31-2.09; P = 0.009). Additionally, HMGB1 levels in peripheral blood were significantly elevated in patients with unexplained recurrent spontaneous abortion (URSA) than those in pregnancy controls (SMD=4.22; 95% CI: 1.64-6.80; P = 0.001) or non-pregnancy controls (SMD=3.87; 95% CI: 1.81-5.92; P = 0.0002). Interestingly, higher blood HMGB1 levels were observed in women with preterm birth (PTB), however, the results did not reach a statistical difference (SMD=0.54; 95% CI: -0.36-1.44; P = 0.24). In conclusion, overexpressed maternal blood HMGB1 levels were associated with adverse pregnancy outcomes, including PE, GDM and URSA. Further studies should be conducted to validate the efficacy of HMGB1 as a biomarker for assessing the risk of adverse pregnancy outcomes.

Association between high-mobility group box 1 levels and preeclampsia: a systematic review and meta-analysis

PURPOSE

Previous studies had demonstrated that high-mobility group box 1 (HMGB1) levels were elevated in preeclampsia (PE). However, the conclusion remains controversial. This study aimed to investigate the association between blood and placenta HMGB1 levels and PE in pregnant women.

METHODS

After a systematic literature search, eligible literature was screened according to inclusion and exclusion criteria. Data extraction and quality assessment were performed independently by two reviewers. The extracted data were analyzed using Review Manager 5.4 and STATA 12.0 software. Subgroup analysis and meta-regression analysis were conducted to find potential sources of heterogeneity.

RESULTS

Twelve studies were included, with a total of 1145 participants. Compared with normal pregnancies, pregnant women with PE had significantly higher blood HMGB1 levels (SMD = 1.34, 95% CI: 0.72-1.95, p < 0.0001). Similarly, the expression of placental HMGB1 in PE was higher than that in normal controls by using Western blot (MD = 0.37, 95% CI: 0.27-0.47, p < 0.00001) or immunohistochemistry (OR = 6.36, 95% CI: 1.48-27.25, p = 0.01). In addition, the blood HMGB1 levels were positively correlated with the severity of PE, with higher blood HMGB1 levels in severe PE than those in mild PE (SMD = 3.35, 95% CI: 0.63-6.06, p = 0.02). The subgroup analysis indicated a close association of blood HMGB1 with PE in the Asian group, but not in the European group.

CONCLUSION

Both blood and placental HMGB1 levels in patients with PE were significantly elevated, and higher blood HMGB1 levels indicated a more serious disease condition, suggesting that higher levels of HMGB1 were associated with the risk of PE.

HMGB1: a double-edged sword and therapeutic target in the female reproductive system

HMGB1 that belongs to the High Mobility Group-box superfamily, is a nonhistone chromatin associated transcription factor. It is present in the nucleus of eukaryotes and can be actively secreted or passively released by kinds of cells. HMGB1 is important for maintaining DNA structure by binding to DNA and histones, protecting it from damage. It also regulates the interaction between histones and DNA, affecting chromatin packaging, and can influence gene expression by promoting nucleosome sliding. And as a DAMP, HMGB1 binding to RAGE and TLRs activates NF-κB, which triggers the expression of downstream genes like IL-18, IL-1β, and TNF-α. HMGB1 is known to be involved in numerous physiological and pathological processes. Recent studies have demonstrated the significance of HMGB1 as DAMPs in the female reproductive system. These findings have shed light on the potential role of HMGB1 in the pathogenesis of diseases in female reproductive system and the possibilities of HMGB1-targeted therapies for treating them. Such therapies can help reduce inflammation and metabolic dysfunction and alleviate the symptoms of reproductive system diseases. Overall, the identification of HMGB1 as a key player in disease of the female reproductive system represents a significant breakthrough in our understanding of these conditions and presents exciting opportunities for the development of novel therapies.

Human intestine and placenta exhibit tissue-specific expression of RAGE isoforms

The receptor for advanced glycation end products (RAGE) is encoded by AGER, a gene that is subjected to tissue-specific alternative splicing. Splice variants of RAGE in intestine and placenta are unknown and contradictory data concerning RAGE protein expression in these tissues have been published. As a basis for future functional studies, we examined RAGE expression in small intestine, colon and placentas. PCR cloning revealed that full-length RAGE is the only RAGE transcript isoform expressed in placenta. In the small intestine, the major transcript isoform detected was RAGE_v1 encoding the C-terminally truncated soluble receptor. In the colon, both full-length RAGE as well as several splice variants were identified. Four antibodies were used to study protein expression by immunoblotting and were carefully validated. Appropriate controls were essential to avoid misinterpretation of bands caused by non-specific reactivity of antibodies. Only one of four antibodies tested detected full-length RAGE in placenta, whereas no RAGE-specific band was detected in intestinal tissues despite loading >30-fold more intestinal tissue than the positive control, human lung. RAGE expression levels in the placenta were 100-fold lower compared with human lung when analyzed by ELISA, and no significant differences in RAGE expression were detected between healthy placentas and placentas from women with preeclampsia, gestational diabetes mellitus, or fetal growth restriction. We conclude that healthy placental chorionic tissue expresses low levels of full-length RAGE, whereas expression of the tissue-specific intestinal isoforms is below the limit of detection. Low RAGE expression levels in combination with a lack of antibody validation may explain the conflicting published results on RAGE protein expression in intestine and placenta.

miRNAs derived from milk small extracellular vesicles inhibit porcine epidemic diarrhea virus infection

Porcine epidemic diarrhea virus (PEDV), a member of the genus Alphacoronavirus in the family Coronaviridae, causes acute diarrhea and/or vomiting, dehydration, and high mortality in neonatal piglets. It has caused huge economic losses to animal husbandry worldwide. Current commercial PEDV vaccines do not provide enough protection against variant and evolved virus strains. No specific drugs are available to treat PEDV infection. The development of more effective therapeutic anti-PEDV agents is urgently needed. Our previous study suggested that porcine milk small extracellular vesicles (sEV) facilitate intestinal tract development and prevent lipopolysaccharide-induced intestinal injury. However, the effects of milk sEV during viral infection remain unclear. Our study found that porcine milk sEV, which was isolated and purified by differential ultracentrifugation, could inhibit PEDV replication in IPEC-J2 and Vero cells. Simultaneously, we constructed a PEDV infection model for piglet intestinal organoids and found that milk sEV also inhibited PEDV infection. Subsequently, in vivo experiments showed that milk sEV pre-feeding exerted robust protection of piglets from PEDV-induced diarrhea and mortality. Strikingly, we found that the miRNAs extracted from milk sEV inhibited PEDV infection. miRNA-seq, bioinformatics analysis, and experimental verification demonstrated that miR-let-7e and miR-27b, which were identified in milk sEV targeted PEDV N and host HMGB1, suppressed viral replication. Taken together, we revealed the biological function of milk sEV in resisting PEDV infection and proved its cargo miRNAs, miR-let-7e and miR-27b, possess antiviral functions. This study is the first description of the novel function of porcine milk sEV in regulating PEDV infection. It provides a better understanding of milk sEV resistance to coronavirus infection, warranting further studies to develop sEV as an attractive antiviral.

Roles of human trophoblasts' pattern recognition receptors in host defense and pregnancy complications

The immune system in pregnancy is able to protect pregnant mothers and fetuses from pathogenic microorganisms even while permitting the mother to tolerate the semi-allogenic fetus. Trophoblasts, which are fetal-derived placental cells, play a central role on both sides of this duality at the maternal-fetal interface. In brief, the trophoblasts express pattern recognition receptors (PRRs) and are involved in the local innate immune response in the placenta. That response eliminates pathogenic microbes but also causes tissue damage. In this review, we summarize the research findings to date regarding the roles of those human trophoblast PRRs. Multiple types of PRRs (Toll-like receptors, Nod-like receptors, and RIG-I-like receptors) are expressed in the placenta and on trophoblasts. Trophoblasts' PRRs participate in protecting the fetus against viruses, bacteria, and parasites by triggering production of proinflammatory cytokines and chemokines in the placenta. On the negative side, PRR signaling in trophoblasts can also initiate inflammation and trophoblast cell death, which can lead to placental inflammation-associated pregnancy complications such as preeclampsia, anti-phospholipid antibody syndrome, and miscarriage. Further elucidation of these dual roles of trophoblasts' PRRs may shed light on the mechanisms by which fetuses are protected against congenital infections and also give us a better understanding of the etiologies of pregnancy complications, which can help us prevent/reduce adverse prenatal/neonatal outcomes.

Second-trimester serum high mobility group box-1 and uterine artery Doppler to predict preeclampsia

The objective of this study was to identify the predictive value for preeclampsia of second-trimester serum high mobility group box-1 (HMGB1) and uterine artery Doppler in singleton pregnancies. Between April 2020 and April 2021, a prospective study was conducted on singleton pregnancies with a gestational age of 16–20⁺⁶ weeks at King Chulalongkorn Memorial Hospital, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Maternal characteristics, uterine artery Doppler, and serum HMGB1 were collected. Serum HMGB1 levels and mean uterine artery pulsatility index (UAPI) were combined to calculate the predictive value for preeclampsia. A total of 393 pregnant women were analyzed, with 25 cases (6.4%) developing preeclampsia and 5 cases (1.3%) developing early-onset preeclampsia. Baseline characteristics of preeclampsia and normal pregnant women were comparable. Preeclamptic pregnant women had significantly higher mean serum HMGB1 levels than normal pregnant women (1112.8 ± 363.1 ng/mL vs 910.8 ± 486.1 ng/mL, p = 0.013). There was no difference in the mean UAPI. Any early-diastolic notching was found more frequently in the preeclampsia group (32.0% vs 12.5%, p = 0.013). The cut-off value for serum HMGB1 levels above 1.04 MoM as abnormal value to predict preeclampsia had sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 88.0%, 53.5%, 11.4% and 98.5%, respectively. When using abnormal serum HMGB1 levels combined with mean UAPI above 95th percentile, the sensitivity, specificity, PPV and NPV to predict preeclampsia were 88.0%, 50.8%, 10.8% and 98.4%, respectively. This study showed that serum HMGB1 at 16–20⁺⁶ weeks of gestation were effective in predicting preeclampsia. The addition of UAPI did not improve the prediction performance.

Kidney-Placenta Crosstalk in health and disease

Organ crosstalk allows the interaction between systems to adapt to a constant changing environment, maintaining homeostasis. The process of placentation and the new hormonal environment during pregnancy trigger physiological changes that modulate kidney function to control extracellular volume, acid-base balance, and filtration of metabolic waste products. The bidirectional communication means that acute or chronic dysfunction of one organ can compromise the other. Abnormal placentation in pregnancy-related hypertensive disorders such as pre-eclampsia and HELLP (haemolysis, elevated liver enzymes and low platelet count) syndrome leads to the release of antiangiogenic factors that may cause kidney injury (thrombotic microangiopathy, glomeruloendotheliosis, mesangiolysis and vasoconstriction of peritubular vessels). These hypertensive disorders are a key cause of kidney injury in gestation, which increases maternal morbi-mortality and adverse foetal outcomes. Conversely, prior kidney injury or causes of kidney injury (diabetes, lupus, glomerulonephritis or other form of chronic kidney disease) increase the risk of developing hypertensive pregnancy disorders, providing a baseline higher risk. Inherited kidney diseases are a special concern, given the potential for genetic predisposition to kidney disease in the foetus. Understanding the bidirectional potential for compromise from placenta to kidney and vice versa provides a better framework to limit damage to both organs and improve maternal and foetal outcomes.

Liposomal chrysin attenuates hepatic ischaemia-reperfusion injury: possible mechanism via inhibiting NLRP3 inflammasome

OBJECTIVES

The chrysin has properties of low aqueous solubility, bioavailability and absorption, and its effect on hepatic ischaemia-reperfusion (HIR) remains unclear. Thus, we prepared a liposomal chrysin (LC) and explored its effect and potential mechanism on HIR.

METHODS

A thin-film dispersion method was used to prepare LC, and a mouse HIR model was used. Mice were pre-treated with LC (100 mg/kg) or placebo by gavage feeding at 16.5 h, 8.5 h, 0.5 h before modelling.

RESULTS

The average particle sizes, polydispersity index, zeta potential, encapsulation efficiency and drug loading of LC were 129 ± 13.53 nm, 0.265 ± 0.021, -34.46 ± 4.14 mV, 95.03 ± 2.17%, 16.4 ± 0.8%. The concentration of chrysin in plasma and liver tissue by LC administration increased 2.54 times and 1.45 times. LC pre-treatment reduced HIR-induced liver injury and inhibited cell apoptosis. Besides, LC pre-treatment decreased reactive oxygen species and malondialdehyde and inhibited the inflammation response indicated by lower IL-6, TNF-α, infiltration of neutrophils. Further, LC pre-treatment significantly decreased NLRP3 activation, evidenced by reduced cleaved caspase-3, NLRP3, ASC, cleaved caspase-1 and IL-1β expression.

CONCLUSIONS

LC has good biocompatibility, and it could attenuate HIR-induced injury. Its mechanism was associated with NLRP3 inflammasome inhibition, and LC might be an effective drug for treating and preventing HIR-induced injury.

A review of key cytokines based on gene polymorphism in the pathogenesis of pre-eclampsia

Although a number of theories have been suggested, including roles for oxidative stress, an abnormal maternal-fetal interface, and genetic and environmental factors, the etiopathology of pre-eclampsia (PE) remains unclear. Maternal immune tolerance is important for maintaining pregnancy, and researchers have increasingly focused on the critical roles of cytokines in the pathogenesis of PE in recent years. The assessment of candidate genetic polymorphisms in PE could partially elucidate the mechanisms of susceptibility to disease, and contribute to seeking for new diagnosis and treatment methods of PE. PE can lead to severe complications, and even the death of both mother and fetus. Although the complex pathology is not yet clear, some evidence suggested that the occurrence of PE is related to inflammatory factors. We reviewed the current understandings of roles of cytokines in PE, and provided an extensive overview of the role of single nucleotide chain polymorphisms (SNPs) in the genes potentially underlying the pathophysiology of PE.

Assembly of Cytoplasmic Stress Granules in Placentas in Women with Preeclampsia

Inflammation is a well-recognized factor associated with preeclampsia (PE). Stress granules (SGs) have been shown to play an important role in regulating inflammation and immune responses. However, whether SGs are involved in the pathogenesis of PE has not been studied. Here, we evaluated the expression of SG components in placenta of pregnancies with PE. Placental samples or serum were collected from PE patients (n = 31) or healthy age-matched pregnancy (n = 17). mRNA expressions of SG-associated genes in placenta from PE or normal pregnancies were detected by real-time quantitative PCR, and protein expressions of HuR and G3BP were detected using western blot. Immunofluorescence staining was performed to evaluate SG components expression in placentas or 10% serum treated HTR-8/Svneo cells using antibodies against HuR and G3BP. Our study showed higher levels of elavl1, lsm2, lsm4, and ago1 mRNA expression and SG marker proteins expression in placental homogenates of PE patients. HuR/G3BP-positive SG structure was further observed in placental villi of PE by immunofluorescence assay. Besides, serum from PE patients could induce SG aggregation in human trophoblast cell line HTR-8/Svneo cells, suggesting the involvement of SGs in the development of PE.

Hypoxia and oxidative stress induce sterile placental inflammation in vitro

Fetal growth restriction (FGR) and stillbirth are associated with placental dysfunction and inflammation and hypoxia, oxidative and nitrative stress are implicated in placental damage. Damage-associated molecular patterns (DAMPs) are elevated in pregnancies at increased risk of FGR and stillbirth and are associated with increase in pro-inflammatory placental cytokines. We hypothesised that placental insults lead to release of DAMPs, promoting placental inflammation. Placental tissue from uncomplicated pregnancies was exposed in vitro to hypoxia, oxidative or nitrative stress. Tissue production and release of DAMPs and cytokines was determined. Oxidative stress and hypoxia caused differential release of DAMPs including uric acid, HMGB1, S100A8, cell-free fetal DNA, S100A12 and HSP70. After oxidative stress pro-inflammatory cytokines (IL-1α, IL-1β, IL-6, IL-8, TNFα, CCL2) were increased both within explants and in conditioned culture medium. Hypoxia increased tissue IL-1α/β, IL-6, IL-8 and TNFα levels, and release of IL-1α, IL-6 and IL-8, whereas CCL2 and IL-10 were reduced. IL1 receptor antagonist (IL1Ra) treatment prevented hypoxia- and oxidative stress-induced IL-6 and IL-8 release. These findings provide evidence that relevant stressors induce a sterile inflammatory profile in placental tissue which can be partially blocked by IL1Ra suggesting this agent has translational potential to prevent placental inflammation evident in FGR and stillbirth.

The Potential Therapeutic Role of the HMGB1-TLR Pathway in Epilepsy

Epilepsy is one of the most common serious neurological disorders, affecting over 70 million people worldwide. For the treatment of epilepsy, antiepileptic drugs (AEDs) and surgeries are widely used. However, drug resistance and adverse effects indicate the need to develop targeted AEDs based on further exploration of the epileptogenic mechanism. Currently, many efforts have been made to elucidate the neuroinflammation theory in epileptogenesis, which may show potential in the treatment of epilepsy. In this respect, an important target protein, high mobility group box 1 (HMGB1), has received increased attention and has been developed rapidly. HMGB1 is expressed in various eukaryotic cells and localized in the cell nucleus. When HMGB1 is released by injuries or diseases, it participates in inflammation. Recent studies suggest that HMGB1 via Toll-like receptor (TLR) pathways can trigger inflammatory responses and play an important role in epilepsy. In addition, studies of HMGB1 have shown its potential in the treatment of epilepsy. Herein, the authors analyzed the experimental and clinical evidence of the HMGB1-TLR pathway in epilepsy to summarize the theory of epileptogenesis and provide insights into antiepileptic therapy in this novel field.

The Immunology of Syncytialized Trophoblast

Multinucleate syncytialized trophoblast is found in three forms in the human placenta. In the earliest stages of pregnancy, it is seen at the invasive leading edge of the implanting embryo and has been called primitive trophoblast. In later pregnancy, it is represented by the immense, multinucleated layer covering the surface of placental villi and by the trophoblast giant cells found deep within the uterine decidua and myometrium. These syncytia interact with local and/or systemic maternal immune effector cells in a fine balance that allows for invasion and persistence of allogeneic cells in a mother who must retain immunocompetence for 40 weeks of pregnancy. Maternal immune interactions with syncytialized trophoblast require tightly regulated mechanisms that may differ depending on the location of fetal cells and their invasiveness, the nature of the surrounding immune effector cells and the gestational age of the pregnancy. Some specifically reflect the unique mechanisms involved in trophoblast cell–cell fusion (aka syncytialization). Here we will review and summarize several of the mechanisms that support healthy maternal–fetal immune interactions specifically at syncytiotrophoblast interfaces.

Decidual and placental NOD1 is associated with inflammation in normal and preeclamptic pregnancies

INTRODUCTION

Inflammation is a normal physiological process that increases to harmful levels in preeclampsia. It affects the interaction between maternal immune cells and fetal trophoblasts at both sites of the maternal-fetal interface; decidua and placenta. The pattern recognition receptor nucleotide-binding oligomerization domain-containing protein (NOD)1 is expressed at both sites. This study aimed to characterize the cellular expression and functionality of NOD1 at the maternal-fetal interface of normal and preeclamptic pregnancies.

METHODS

Women with normal or preeclamptic pregnancies delivered by caesarean section were included. Decidual (n = 90) and placental (n = 91) samples were analyzed for NOD1 expression by immunohistochemistry and an automated image-based quantification method. Decidual and placental explants were incubated with or without the NOD1-agonist iE-DAP and cytokine responses measured by ELISA.

RESULTS

NOD1 was markedly expressed by maternal cells in the decidua and by fetal trophoblasts in both decidua and placenta, with trophoblasts showing the highest NOD1 expression. Preeclampsia with normal fetal growth was associated with a trophoblast-dependent increase in decidual NOD1 expression density. Compared to normal pregnancies, preeclampsia demonstrated stronger correlation between decidual and placental NOD1 expression levels. Increased production of interleukin (IL)-6 or IL-8 after in vitro explant stimulation confirmed NOD1 functionality.

DISCUSSION

These findings suggest that NOD1 contributes to inflammation at the maternal-fetal interface in normal pregnancies and preeclampsia and indicate a role in direct maternal-fetal communication. The strong expression of NOD1 by all trophoblast types highlights the importance of combined assessment of decidua and placenta for overall understanding of pathophysiological processes at the maternal-fetal interface.

In Utero Exposure to Fine Particles Decreases Early Birth Weight of Rat Offspring and TLR4/NF-κB Expression in Lungs

Particulate matter (PM2.5) exposure is reported to have deleterious effects on health. Maternal PM2.5 exposure has been confirmed to damage the growth of somatic cells and enhance the incidence of chronic respiratory diseases in children. Here we aim to investigate the impact of in utero PM2.5 exposure on early birth weight and postnatal lung development. Pregnant Sprague-Dawley rats were administered PM2.5 (0.1, 0.5, 2.5, or 7.5 mg/kg) intraperitoneally every 3 days until birth. Maternal and birth outcomes and somatic growth were monitored. Lungs were collected on PND1 (where PND = postnatal day) and PND28; the lung wet-to-dry weight ratio (W/D) was analyzed, and reactive oxygen species (ROS) levels were measured. Expression of Toll-like receptor 4 (TLR4) and NF-κB were evaluated by Western blotting and quantitative RT-PCR. There were no significant intergroup differences for maternal outcomes; however, offspring exposed in utero to 2.5 and 7.5 mg/kg PM2.5 were significantly smaller in litter weight than the controls. In utero exposure to 2.5 and 7.5 mg/kg PM2.5 led to lower body weight after birth and disrupted lung development during infancy. ROS levels were significantly increased in the 7.5 mg/kg PM2.5 group. PM2.5-treated rats showed upregulated pulmonary expression of TLR4 and NF-κB. Maternal PM2.5 exposure enhances the risk of low birth weight and affects lung alveolar development. The underlying molecular mechanisms may involve TLR4/NF-κB signaling.

High-mobility group box 1 is a driver of inflammation throughout pregnancy

A proinflammatory response driven by high-mobility group box 1 (HMGB1) is important for the success of both the early stages of pregnancy and parturition initiation. However, the tight regulation of HMGB1 within these two stages is critical, as increased HMGB1 can manifest into pregnancy-related pathologies. Although during the early stages of pregnancy HMGB1 is critical for the development and implantation of the embryo, and uterine decidualization, high levels within the uterine cavity have been linked to pregnancy failure. In addition, chronic inflammation, resultant from increased HMGB1 within the maternal circulation and gestational tissues, also increases the risk for preterm labor, preterm birth, or infant mortality. Due to the link between HMGB1 and several pregnancy pathologies, the possibility of leveraging HMGB1 as a biomarker has been assessed. However, data are limited that demonstrate how known HMGB1 inhibitors could reduce inflammation within pregnancy. Thus, further research is warranted to improve our understanding of the potential of HMGB1 as a therapeutic target to reduce inflammation within pregnancy. This review aims to describe what is understood about the role of HMGB1 that drives inflammation throughout pregnancy and highlight its potential as a biomarker and therapeutic target within this context.

TLR3 expression by maternal and fetal cells at the maternal-fetal interface in normal and preeclamptic pregnancies

Inflammation and oxidative stress at the maternal-fetal interface characterize the placental dysfunction that underlies the pregnancy disorder preeclampsia. Specialized fetal trophoblasts directly interact with leukocytes at both sites of the maternal-fetal interface; the uterine wall decidua; and the placenta. TLR3 has been implicated in the harmful inflammation at the maternal-fetal interface in preeclampsia, but the cellular involvement in the decidua and placenta has not been determined. This study aimed to characterize and quantify cell-specific TLR3 expression and function at the maternal-fetal interface in normal and preeclamptic pregnancies. TLR3 expression was assessed by immunohistochemistry and quantified by a novel image-based and cell-specific quantitation method. TLR3 was expressed at the maternal-fetal interface by all decidual and placental trophoblast types and by maternal and fetal leukocytes. Placental, but not decidual, TLR3 expression was significantly higher in preeclampsia compared to normal pregnancies. This increase was attributed to placental intravillous tissue and associated with both moderate and severe placental dysfunction. TLR3 pathway functionality in the decidua and placenta was confirmed by TLR3 ligand-induced cytokine response, but the TLR3 expression levels did not correlate between the two sites. In conclusion, functional TLR3 was broadly expressed by maternal and fetal cells at both sites of the maternal-fetal interface and the placental intravillous expression was increased in preeclampsia. This suggests TLR3-mediated inflammatory involvement with local regulation at both sites of the maternal-fetal interface in normal and preeclamptic pregnancies.

Maternal Obesity and the Uterine Immune Cell Landscape: The Shaping Role of Inflammation

Inflammation is often equated to the physiological response to injury or infection. Inflammatory responses defined by cytokine storms control cellular mechanisms that can either resolve quickly (i.e., acute inflammation) or remain prolonged and unabated (i.e., chronic inflammation). Perhaps less well-appreciated is the importance of inflammatory processes central to healthy pregnancy, including implantation, early stages of placentation, and parturition. Pregnancy juxtaposed with disease can lead to the perpetuation of aberrant inflammation that likely contributes to or potentiates maternal morbidity and poor fetal outcome. Maternal obesity, a prevalent condition within women of reproductive age, associates with increased risk of developing multiple pregnancy disorders. Importantly, chronic low-grade inflammation is thought to underlie the development of obesity-related obstetric and perinatal complications. While diverse subsets of uterine immune cells play central roles in initiating and maintaining healthy pregnancy, uterine leukocyte dysfunction as a result of maternal obesity may underpin the development of pregnancy disorders. In this review we discuss the current knowledge related to the impact of maternal obesity and obesity-associated inflammation on uterine immune cell function, utero-placental establishment, and pregnancy health.

The immune system and microbiome in pregnancy

Hormonal changes during pregnancy instigate numerous physiological changes aimed at the growth and delivery of a healthy baby. A careful balance between immunological tolerance against fetal antigens and immunity against infectious agents needs to be maintained. A three-way interaction between pregnancy hormones, the immune system and our microbiota is now emerging. Recent evidence suggests that microbial alterations seen during pregnancy may help maintain homeostasis and aid the required physiological changes occurring in pregnancy. However, these same immunological and microbial alterations may also make women more vulnerable during pregnancy and the post-partum period, especially regarding immunological and infectious diseases. Thus, a further understanding of the host-microbial interactions taking place during pregnancy may improve identification of populations at risk for adverse pregnancy outcomes.

Hydroxychloroquine may be beneficial in preeclampsia and recurrent miscarriage

Recurrent miscarriage (RM) and vasculoplacental disorders, such as preeclampsia (PE), affect women of childbearing age worldwide. Vascular endothelial dysfunction and immunological impairment are associated with both RM and PE. To date, there is no effective or optimal therapeutic approach for these conditions. Notably, aspirin use is only partially effective in the prevention of PE. Hydroxychloroquine (HCQ) has demonstrated beneficial effects on disease flares, pregnancy outcomes and cardiovascular impairment in systemic erythaematosus lupus (SLE) through its immunomodulatory, vasculoprotective and antithrombotic properties. Here, in the context of the underlying physiological dysregulation associated with PE and RM, the beneficial properties and potential therapeutic efficacy of HCQ are reviewed in anticipation of the results of current and future trials. Two related trials addressing RM in the absence of maternal autoimmune disease are ongoing. Other trials addressing pregnancy outcomes in the presence of maternal autoimmune disease are forthcoming. In this review, we hypothesise that the immunological and endothelial effects of HCQ may be beneficial in the context of PE and RM, regardless of the maternal autoimmune status.