IL-1 signaling mediates intrauterine inflammation and chorio-decidua neutrophil recruitment and activation

TLR8-activating miR-146a-3p is an intermediate signal contributing to fetal membrane inflammation in response to bacterial LPS

Preterm birth is the largest contributor to neonatal morbidity and is often associated with chorioamnionitis, defined as inflammation/infection of the fetal membranes (FMs). Chorioamnionitis is characterised by neutrophil infiltration of the FMs and is associated with elevated levels of the neutrophil chemoattractant, interleukin (IL)-8 and the proinflammatory cytokine, IL-1β. While FMs can respond to infections through innate immune sensors, such as toll-like receptors (TLRs), the downstream mechanisms by which chorioamnionitis arises are not fully understood. A novel group of non-classical microRNAs (miR-21a, miR-29a, miR-146a-3p, Let-7b) function as endogenous danger signals by activating the ssRNA viral sensors TLR7 and TLR8. In this study, the pro-inflammatory roles of TLR7/TLR8-activating miRs were examined as mediators of FM inflammation in response to bacterial lipopolysaccharide (LPS) using an in vitro human FM explant system, an in vivo mouse model of pregnancy, and human clinical samples. Following LPS exposure, miR-146a-3p was significantly increased in both human FM explants and wild-type mouse FMs. Expression of miR-146a-3p was also significantly elevated in FMs from women with preterm birth and chorioamnionitis. FM IL-8 and inflammasome-mediated IL-1β production in response to LPS was dependent on miR-146a-3p and TLR8 downstream of TLR4 activation. In wild-type mice, LPS exposure increased FM IL-8 and IL-1β production and induced preterm birth. In TLR7-/-/TLR8-/- mice, LPS exposure was able to initiate but not sustain preterm birth, and FM inflammation was reduced. Together, we demonstrate a novel signalling mechanism at the maternal-fetal interface in which TLR8-activating miR-146a-3p acts as an intermediate danger signal to drive FM inflammasome-dependent and -independent mechanisms of inflammation and, thus, may play a role in chorioamnionitis and subsequent preterm birth.

Protocol for isolating amnion cells from human and non-human primate placenta for flow cytometry and transcriptomics

The amnion is a thin layer of fetal origin in contact with the amniotic fluid which plays a key role at the feto-maternal interface during pregnancy. Here, we present a protocol for isolation of human and Rhesusmacaque amnion cells. We describe steps for tissue dissection, cell isolation for flow cytometry analysis, and RNA isolation for RNA sequencing library preparation and analysis. This protocol can provide insights into altered immunological pathways during intrauterine infections to develop new therapeutic strategies. For complete details on the use and execution of this protocol, please refer to Presicce et al.1.

IL-1 and TNF mediates IL-6 signaling at the maternal-fetal interface during intrauterine inflammation

Introduction

IL6 signaling plays an important role in triggering labor and IL6 is an established biomarker of intrauterine infection/inflammation (IUI) driven preterm labor (PTL). The biology of IL6 during IUI at the maternal-fetal interface was investigated in samples from human subjects and non-human primates (NHP).

Methods

Pregnant women with histologic chorioamnionitis diagnosed by placenta histology were recruited (n=28 term, n=43 for preterm pregnancies from 26-36 completed weeks of gestation). IUI was induced in Rhesus macaque by intraamniotic injection of lipopolysachharide (LPS, n=23). IL1 signaling was blocked using Anakinra (human IL-1 receptor antagonist, n=13), and Tumor necrosis factor (TNF) signaling was blocked by anti TNF-antibody (Adalimumab n=14). The blockers were given before LPS. All animals including controls (intraamniotic injection of saline n=27), were delivered 16h after LPS/saline exposure at about 80% gestation.

Results

IUI induced a robust expression of IL6 mRNAs in the fetal membranes (chorion-amnion-decidua tissue) both in humans (term and preterm) and NHP. The major sources of IL6 mRNA expression were the amnion mesenchymal cells (AMC) and decidua stroma cells. Additionally, during IUI in the NHP, ADAM17 (a protease that cleaves membrane bound IL6 receptor (IL6R) to release a soluble form) and IL6R mRNA increased in the fetal membranes, and the ratio of IL6 and soluble forms of IL6R, gp130 increased in the amniotic fluid signifying upregulation of IL6 trans-signaling. Both IL1 and TNF blockade suppressed LPS-induced IL6 mRNAs in the AMC and variably decreased elements of IL6 trans-signaling.

Discussion

These data suggest that IL1 and TNF blockers may be useful anti-inflammatory agents via suppression of IL6 signaling at the maternal-fetal interface.

Preventing Preterm Birth: Exploring Innovative Solutions

This review examines the complexities of preterm birth (PTB), emphasizes the pivotal role of inflammation in the pathogenesis of preterm labor, and assesses current available interventions. Antibiotics, progesterone analogs, mechanical approaches, nonsteroidal anti-inflammatory drugs, and nutritional supplementation demonstrate a limited efficacy. Tocolytic agents, targeting uterine activity and contractility, inadequately prevent PTB by neglecting to act on uteroplacental inflammation. Emerging therapies targeting toll-like receptors, chemokines, and interleukin receptors exhibit promise in mitigating inflammation and preventing PTB.

Membrane inflammasome activation by choriodecidual Ureaplasma parvum infection without intra-amniotic infection in a Non-Human Primate model†

Intrauterine infection is a significant cause of neonatal morbidity and mortality. Ureaplasma parvum is a microorganism commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms of early stage ascending reproductive tract infection remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes we utilized a non-human primate (NHP) model of choriodecidual U. parvum infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at ~105-112 days gestation and choriodecidual inoculation with U. parvum (105 CFU/mL, n =4) or sterile media (controls; n = 4) starting at 115-119 days, repeated at 5-day intervals until C-section at 136-140 days (term=167 days). The average inoculation to delivery interval was 21 days, and Ureaplasma infection of the amniotic fluid (AF) was undetectable in all animals. Choriodecidual Ureaplasma infection resulted in increased fetal membrane expression of MMP-9 and PTGS2, but did not result in preterm labor or increased concentrations of AF pro-inflammatory cytokines. However, membrane expression of inflammasome sensors, NLRP3, NLRC4, AIM2, and NOD2, and adaptor ASC (PYCARD) gene expression were significantly increased. Gene expression of IL-1β, IL-18, IL-18R1  , CASPASE-1, and pro-CASPASE-1 protein increased with Ureaplasma infection. Downstream inflammatory genes MYD88 and NFκB (Nuclear factor kappa-light-chain-enhancer of activated B cells) were also significantly upregulated. These results demonstrate that choriodecidual Ureaplasma infection, can cause activation of inflammasome complexes and pathways associated with pPROM and preterm labor prior to microbes being detectable in the AF.

Chorioamnionitis accelerates granule cell and oligodendrocyte maturation in the cerebellum of preterm nonhuman primates

BACKGROUND

Preterm birth is often associated with chorioamnionitis and leads to increased risk of neurodevelopmental disorders, such as autism. Preterm birth can lead to cerebellar underdevelopment, but the mechanisms of disrupted cerebellar development in preterm infants are not well understood. The cerebellum is consistently affected in people with autism spectrum disorders, showing reduction of Purkinje cells, decreased cerebellar grey matter, and altered connectivity.

METHODS

Preterm rhesus macaque fetuses were exposed to intra-amniotic LPS (1 mg, E. coli O55:B5) at 127 days (80%) gestation and delivered by c-section 5 days after injections. Maternal and fetal plasma were sampled for cytokine measurements. Chorio-decidua was analyzed for immune cell populations by flow cytometry. Fetal cerebellum was sampled for histology and molecular analysis by single-nuclei RNA-sequencing (snRNA-seq) on a 10× chromium platform. snRNA-seq data were analyzed for differences in cell populations, cell-type specific gene expression, and inferred cellular communications.

RESULTS

We leveraged snRNA-seq of the cerebellum in a clinically relevant rhesus macaque model of chorioamnionitis and preterm birth, to show that chorioamnionitis leads to Purkinje cell loss and disrupted maturation of granule cells and oligodendrocytes in the fetal cerebellum at late gestation. Purkinje cell loss is accompanied by decreased sonic hedgehog signaling from Purkinje cells to granule cells, which show an accelerated maturation, and to oligodendrocytes, which show accelerated maturation from pre-oligodendrocytes into myelinating oligodendrocytes.

CONCLUSION

These findings suggest a role of chorioamnionitis on disrupted cerebellar maturation associated with preterm birth and on the pathogenesis of neurodevelopmental disorders among preterm infants.

Potential roles of the interactions between gut microbiota and metabolites in LPS-induced intrauterine inflammation (IUI) and associated preterm birth (PTB)

BACKGROUND

Prenatal exposure to intrauterine inflammation (IUI) is a crucial event in preterm birth (PTB) pathophysiology, increasing the incidence of neurodevelopmental disorders. Gut microbiota and metabolite profile alterations have been reported to be involved in PTB pathophysiology.

METHOD AND RESULTS

In this study, IUI-exposed PTB mouse model was established and verified by PTB rate and other perinatal adverse reactions; LPS-indued IUI significantly increased the rates of PTB, apoptosis and inflammation in placenta tissue samples. LPS-induced IUI caused no significant differences in species richness and evenness but significantly altered the species abundance distribution. Non-targeted metabolomics analysis indicated that the metabolite profile of the preterm mice was altered, and differential metabolites were associated with signaling pathways including pyruvate metabolism. Furthermore, a significant positive correlation between Parasutterella excrementihominis and S4572761 (Nb-p-coumaroyltryptamine) and Mreference-1264 (pyruvic acid), respectively, was observed. Lastly, pyruvic acid treatment partially improved LPS-induced IUI phenotypes and decreased PTB rates and decreased the apoptosis and inflammation in placenta tissue samples.

CONCLUSION

This study revealed an association among gut microbiota dysbiosis, metabolite profile alterations, and LPS-induced IUI and PTB in mice models. Our investigation revealed the possible involvement of gut microbiota in the pathophysiology of LPS-induced IUI and PTB, which might be mediated by metabolites such as pyruvic acid. Future studies should be conducted to verify the findings through larger sample-sized animal studies and clinical investigations.

Addressing a broken drug pipeline for preterm birth: why early preterm birth is an orphan disease

Preterm birth remains one of the most urgent unresolved medical problems in obstetrics, yet only 2 therapeutics for preventing preterm birth have ever been approved by the United States Food and Drug Administration, and neither remains on the market. The recent withdrawal of 17-hydroxyprogesterone caproate (17-OHPC, Makena) marks a new but familiar era for obstetrics with no Food and Drug Administration-approved pharmaceuticals to address preterm birth. The lack of pharmaceuticals reflects a broad and ineffective pipeline hindered by extensive regulatory hurdles, soaring costs of performing drug research, and concerns regarding adverse effects among a particularly vulnerable population. The pharmaceutical industry has historically limited investments in research for diseases with similarly small markets, such as cystic fibrosis, given their rarity and diminished projected financial return. The Orphan Drug Act, however, incentivizes drug development for "orphan diseases", defined as affecting <200,000 people in the United States annually. Although the total number of preterm births in the United States exceeds this threshold annually, the early subset of preterm birth (<34 weeks' gestation) would qualify, which is predominantly caused by inflammation and infection. The scientific rationale for classifying preterm birth into early and late subsets is strong given that their etiologies differ, and therapeutics that may be efficacious for one subset may not work for the other. For example, antiinflammatory therapeutics would be expected to be highly effective for early but not late preterm birth. A robust therapeutic pipeline of antiinflammatory drugs already exists, which could be used to target spontaneous early preterm birth, in combination with antibiotics shown to sterilize the amniotic cavity. New applications for therapeutics targeting spontaneous early preterm birth could categorize as orphan disease drugs, which could revitalize the preterm birth therapeutic pipeline. Herein, we describe why drugs targeting early preterm birth should qualify for orphan status, which may increase pharmaceutical interest for this vitally important obstetrical condition.

Amnion responses to intrauterine inflammation and effects of inhibition of TNF signaling in preterm Rhesus macaque

Intrauterine infection/inflammation (IUI) is a frequent complication of pregnancy leading to preterm labor and fetal inflammation. How inflammation is modulated at the maternal-fetal interface is unresolved. We compared transcriptomics of amnion (a fetal tissue in contact with amniotic fluid) in a preterm Rhesus macaque model of IUI induced by lipopolysaccharide with human cohorts of chorioamnionitis. Bulk RNA sequencing (RNA-seq) amnion transcriptomic profiles were remarkably similar in both Rhesus and human subjects and revealed that induction of key labor-mediating genes such as IL1 and IL6 was dependent on nuclear factor κB (NF-κB) signaling and reversed by the anti-tumor necrosis factor (TNF) antibody Adalimumab. Inhibition of collagen biosynthesis by IUI was partially restored by Adalimumab. Interestingly, single-cell transcriptomics, flow cytometry, and immunohistology demonstrated that a subset of amnion mesenchymal cells (AMCs) increase CD14 and other myeloid cell markers during IUI both in the human and Rhesus macaque. Our data suggest that CD14+ AMCs represent activated AMCs at the maternal-fetal interface.

The role of neutrophils in chorioamnionitis

Chorioamnionitis, commonly referred to as intrauterine infection or inflammation, is pathologically defined by neutrophil infiltration and inflammation at the maternal-fetal interface. Chorioamnionitis is the common complication during late pregnancy, which lead to a series of serious consequences, such as preterm labor, preterm premature rupture of the fetal membranes, and fetal inflammatory response syndrome. During infection, a large number of neutrophils migrate to the chorio-decidua in response to chemokines. Although neutrophils, a crucial part of innate immune cells, have strong anti-inflammatory properties, over-activating them can harm the body while also eliminating pathogens. This review concentrated on the latest studies on chorioamnionitis-related consequences as well as the function and malfunction of neutrophils. The release of neutrophil extracellular traps, production of reactive oxygen species, and degranulation from neutrophils during intrauterine infection, as well as their pathological roles in complications related to chorioamnionitis, were discussed in detail, offering fresh perspectives on the treatment of chorioamnionitis.

The eNAMPT/TLR4 inflammatory cascade drives the severity of intra-amniotic inflammation in pregnancy and predicts infant outcomes

Introduction: Intra-amniotic inflammation (IAI) or chorioamnionitis is a common complication of pregnancy producing significant maternal morbidity/mortality, premature birth and neonatal risk of chronic lung diseases such as bronchopulmonary dysplasia (BPD). We examined eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a critical inflammatory DAMP and TLR4 ligand, as a potential therapeutic target to reduce IAI severity and improve adverse fetal/neonatal outcomes. Methods: Blood/tissue samples were examined in: 1) women with histologically-proven chorioamnionitis, 2) very low birth weight (VLBW) neonates, and 3) a preclinical murine pregnancy model of IAI. Groups of pregnant IAI-exposed mice and pups were treated with an eNAMPT-neutralizing mAb. Results: Human placentas from women with histologically-proven chorioamnionitis exhibited dramatic NAMPT expression compared to placentas without chorioamnionitis. Increased NAMPT expression in whole blood from VLBW neonates (day 5) significantly predicted BPD development. Compared to untreated LPS-challenged murine dams (gestational day 15), pups born to eNAMPT mAb-treated dams (gestational days 15/16) exhibited a > 3-fold improved survival, reduced neonate lung eNAMPT/cytokine levels, and reduced development and severity of BPD and pulmonary hypertension (PH) following postnatal exposure to 100% hyperoxia days 1-14. Genome-wide gene expression studies of maternal uterine and neonatal cardiac tissues corroborated eNAMPT mAb-induced reductions in inflammatory pathway genes. Discussion: The eNAMPT/TLR4 inflammatory pathway is a highly druggable contributor to IAI pathobiology during pregnancy with the eNAMPT-neutralizing mAb a novel therapeutic strategy to decrease premature delivery and improve short- and long-term neonatal outcomes. eNAMPT blood expression is a potential biomarker for early prediction of chronic lung disease among premature neonates.

Proteomic analysis of plasma to identify novel biomarkers for intra-amniotic infection and/or inflammation in preterm premature rupture of membranes

To identify potential plasma biomarkers associated with microbial invasion of the amniotic cavity (MIAC) and/or intraamniotic inflammation (IAI) in women with preterm premature rupture of membranes (PPROM). This retrospective cohort study included 182 singleton pregnant women with PPROM (23-33 weeks) who underwent amniocentesis. Plasma samples; all subjects were chosen from these participants and were analyzed using label-free liquid chromatography-tandem mass spectrometry for proteome profiling using a nested case-control study design (cases with MIAC/IAI vs. non-MIAC/IAI controls [n = 9 each]). Three identified target molecules for MIAC/IAI were further verified by ELISA in the study cohort (n = 182). Shotgun proteomic analysis revealed 17 differentially expressed proteins (P < 0.05) in the plasma of MIAC/IAI cases. In particular, the levels of FCGR3A and haptoglobin, but not LRP1, were found to be increased in the plasma of patients with MIAC, IAI, and both MIAC/IAI compared with those without these conditions. Moreover, these differences remained significant after adjusting for gestational age at sampling. The area under the curves of plasma FCGR3A and haptoglobin ranged within 0.59-0.65 with respect to each of the three outcome measures. Plasma FCGR3A and haptoglobin were identified as potential independent biomarkers for less-invasively detecting MIAC/IAI in women with PPROM.

Hearing screening test in neonates born to COVID-19-positive mothers

SARS-CoV-2, the responsible virus for the COVID-19 pandemic, has demonstrated neurotropic properties indicated by cases presenting with auditory and vestibular system insults. The expression of ACE-2 receptors in the placenta and the detection of IgM antibodies against the virus in the fetuses of pregnant women suffering from COVID-19 render vertical transmission of the infection to the fetus possible. Thus, our study aims to examine whether, similar to other viruses like CMV, SARS-CoV-2 is responsible for congenital hearing loss. This is a retrospective study in a regional pediatric hospital. The medical records of newborns (n = 111) born by mothers positive for COVID-19 during pregnancy who underwent screening hearing tests with Transient Evoked Otoacoustic Emissions (TEOAE) and Automatic Auditory Brainstem Response (AABR) from February 2020 to June 2022 were reviewed. Neonates with additional aggravating factors for congenital hearing loss were excluded from the study. For the study period, nine mothers were found positive during the first trimester, twenty mothers in the second trimester, and eighty-three mothers in the third trimester. TEOAEs test and AABR test scored PASS bilaterally in all neonates tested.

CONCLUSION

Infection with COVID-19 during pregnancy was not a risk factor for hearing loss, similar to other studies.

WHAT IS KNOWN

• The pathogenetic mechanism of the viral-induced impairment of the organ of Corti includes direct damage to the hair cells and indirect damage due to the induction of the innate inflammatory response. • Early data suggested that the SARS-CoV-2 virus also has neurotropic properties with manifestations from the sensory epithelia.

WHAT IS NEW

• Although the intrauterine infection remains controversial, the expression of the ACE-2 receptor on the placenta and the detection of IgM antibodies, as well as the covid-19 genome in fetuses, make the vertical transmission tenable. • In our study, the newborn hearing screening results indicate that COVID-19 infection during pregnancy is not a risk factor for hearing loss.

The role of interleukin-1 in perinatal inflammation and its impact on transitional circulation

Preterm birth is defined as delivery at <37 weeks of gestational age (GA) and exposes 15 million infants worldwide to serious early life diseases. Lowering the age of viability to 22 weeks GA entailed provision of intensive care to a greater number of extremely premature infants. Moreover, improved survival, especially at extremes of prematurity, comes with a rising incidence of early life diseases with short- and long-term sequelae. The transition from fetal to neonatal circulation is a substantial and complex physiologic adaptation, which normally happens rapidly and in an orderly sequence. Maternal chorioamnionitis or fetal growth restriction (FGR) are two common causes of preterm birth that are associated with impaired circulatory transition. Among many cytokines contributing to the pathogenesis of chorioamnionitis-related perinatal inflammatory diseases, the potent pro-inflammatory interleukin (IL)-1 has been shown to play a central role. The effects of utero-placental insufficiency-related FGR and in-utero hypoxia may also be mediated, in part, via the inflammatory cascade. In preclinical studies, blocking such inflammation, early and effectively, holds great promise for improving the transition of circulation. In this mini-review, we outline the mechanistic pathways leading to abnormalities in transitional circulation in chorioamnionitis and FGR. In addition, we explore the therapeutic potential of targeting IL-1 and its influence on perinatal transition in the context of chorioamnionitis and FGR.

Term and Preterm Birth Initiation Is Associated with the Macrophages Shifting to M1 Polarization in Gestational Tissues in Mice

Inflammation in gestational tissues plays critical role in parturition initiation. We sought to investigate the leukocyte infiltration and cytokine profile in uterine tissues to understand the inflammation during term and preterm labor in the mouse model. Preterm birth was induced by the administration of lipopolysaccharide (LPS) or RU38486. The populations of leukocytes were determined by flow cytometry. Macrophages were the largest population in the myometrium and decidua in late gestation. The macrophage population was significantly changed in the myometrium and decidua from late pregnancy to term labor and significantly changed at LPS- and RU386-induced preterm labor. Neutrophils, T cells, and NKT cells were increased in LPS- and RU38486-induced preterm labor. The above changes were accompanied by the increased expression of cytokines and chemokines. In late gestation, M2 macrophages were the predominant phenotype in gestational tissues. M1 macrophages significantly increased in these tissues at term and preterm labor. IL-6 and NLRP3 expression was significantly increased in macrophages at labor, supporting that macrophages exhibit proinflammatory phenotypes. NLRP3 inflammasome inhibitor MCC950 mainly suppressed macrophage infiltration in the myometrium at term labor and preterm labor. Our data suggest that the M1 polarization of macrophages contributes to inflammation linked to term and preterm labor initiation in gestational tissues.

Actualidad en corioamnionitis

La corioamnionitis se ha relacionados con desenlaces desfavorables en el período prenatal y neonatal (abortos, parto pretérmino, sepsis neonatal, entre otros), además de implicaciones a largo plazo en la infancia, tales como alteraciones en el coeficiente intelectual. Por esta razón es de vital importancia el diagnóstico histopatológico oportuno. En este artículo se revisará el abordaje histopatológico de la corioamnionitis, su estadificación e implicaciones clínicas.

The Immediate Early Response of Lens Epithelial Cells to Lens Injury

Cataracts are treated by lens fiber cell removal followed by intraocular lens (IOL) implantation into the lens capsule. While effective, this procedure leaves behind numerous lens epithelial cells (LECs) which undergo a wound healing response that frequently leads to posterior capsular opacification (PCO). In order to elucidate the acute response of LECs to lens fiber cell removal which models cataract surgery (post cataract surgery, PCS), RNA-seq was conducted on LECs derived from wild type mice at 0 and 6 h PCS. This analysis found that LECs upregulate the expression of numerous proinflammatory cytokines and profibrotic regulators by 6 h PCS suggesting rapid priming of pathways leading to inflammation and fibrosis PCS. LECs also highly upregulate the expression of numerous immediate early transcription factors (IETFs) by 6 h PCS and immunolocalization found elevated levels of these proteins by 3 h PCS, and this was preceded by the phosphorylation of ERK1/2 in injured LECs. Egr1 and FosB were among the highest expressed of these factors and qRT-PCR revealed that they also upregulate in explanted mouse lens epithelia suggesting potential roles in the LEC injury response. Analysis of lenses lacking either Egr1 or FosB revealed that both genes may regulate a portion of the acute LEC injury response, although neither gene was essential for expression of either proinflammatory or fibrotic markers at later times PCS suggesting that IETFs may work in concert to mediate the LEC injury response following cataract surgery.

Spontaneous preterm birth: Involvement of multiple feto-maternal tissues and organ systems, differing mechanisms, and pathways

Survivors of preterm birth struggle with multitudes of disabilities due to improper in utero programming of various tissues and organ systems contributing to adult-onset diseases at a very early stage of their lives. Therefore, the persistent rates of low birth weight (birth weight < 2,500 grams), as well as rates of neonatal and maternal morbidities and mortalities, need to be addressed. Active research throughout the years has provided us with multiple theories regarding the risk factors, initiators, biomarkers, and clinical manifestations of spontaneous preterm birth. Fetal organs, like the placenta and fetal membranes, and maternal tissues and organs, like the decidua, myometrium, and cervix, have all been shown to uniquely respond to specific exogenous or endogenous risk factors. These uniquely contribute to dynamic changes at the molecular and cellular levels to effect preterm labor pathways leading to delivery. Multiple intervention targets in these different tissues and organs have been successfully tested in preclinical trials to reduce the individual impacts on promoting preterm birth. However, these preclinical trial data have not been effectively translated into developing biomarkers of high-risk individuals for an early diagnosis of the disease. This becomes more evident when examining the current global rate of preterm birth, which remains staggeringly high despite years of research. We postulate that studying each tissue and organ in silos, as how the majority of research has been conducted in the past years, is unlikely to address the network interaction between various systems leading to a synchronized activity during either term or preterm labor and delivery. To address current limitations, this review proposes an integrated approach to studying various tissues and organs involved in the maintenance of normal pregnancy, promotion of normal parturition, and more importantly, contributions towards preterm birth. We also stress the need for biological models that allows for concomitant observation and analysis of interactions, rather than focusing on these tissues and organ in silos.

Genetics, epigenetics, and transcriptomics of preterm birth

Preterm birth contributes significantly to neonatal mortality and morbidity. Despite its global significance, there has only been limited progress in preventing preterm birth. Spontaneous preterm birth (sPTB) results from a wide variety of pathological processes. Although many non-genetic risk factors influence the timing of gestation and labor, compelling evidence supports the role of substantial genetic and epigenetic influences and their interactions with the environment contributing to sPTB. To investigate a common and complex disease such as sPTB, various approaches such as genome-wide association studies, whole-exome sequencing, transcriptomics, and integrative approaches combining these with other 'omics studies have been used. However, many of these studies were typically small or focused on a single ethnicity or geographic region with limited data, particularly in populations at high risk for sPTB, or lacked a robust replication. These studies found many genes involved in the inflammation and immunity-related pathways that may affect sPTB. Recent studies also suggest the role of epigenetic modifications of gene expression by the environmental signals as a potential contributor to the risk of sPTB. Future genetic studies of sPTB should continue to consider the contributions of both maternal and fetal genomes as well as their interaction with the environment.

A potent myeloid response is rapidly activated in the lungs of premature Rhesus macaques exposed to intra-uterine inflammation

Up to 40% of preterm births are associated with histological chorioamnionitis (HCA), which leads to elevated levels of pro-inflammatory mediators and microbial products in the amniotic fluid, which come in contact with fetal lungs. Yet, fetal pulmonary immune responses to such exposure remain poorly characterized. To address this gap, we used our established HCA model, in which pregnant Rhesus macaques receive intraamniotic (IA) saline or LPS. IA LPS induced a potent and rapid myeloid cell response in fetal lungs, dominated by neutrophils and monocytes/macrophages. Infiltrating and resident myeloid cells exhibited transcriptional profiles consistent with exposure to TLR ligands, as well as cytokines, notably IL-1 and TNFα. Although simultaneous, in vivo blockade of IL-1 and TNFα signaling did not prevent the inflammatory cell recruitment, it blunted the lung overall inflammatory state reducing communication between, and activation of, infiltrating immune cells. Our data indicate that the fetal innate immune system can mount a rapid multi-faceted pulmonary immune response to in utero exposure to inflammation. These data provide mechanistic insights into the association between HCA and the postnatal lung morbidities of the premature infant and highlight therapeutic potential of inflammatory blockade in the fetus.

Reduction of lactoferrin aggravates neuronal ferroptosis after intracerebral hemorrhagic stroke in hyperglycemic mice

Diabetic hyperglycemia aggravates the prognosis of intracerebral hemorrhagic stroke (ICH) in the clinic. In addition to hematoma expansion and increased inflammation, how diabetic hyperglycemia affects the outcomes of ICH is still unclear. We found that streptozotocin-induced diabetic hyperglycemia not only increased neutrophil infiltration, but also changed the gene expression profile of neutrophils, including lactoferrin (Ltf) encoding gene Ltf. Peroxisome proliferator-activated receptor γ (PPARγ) transcribed Ltf and the lack of neutrophilic Ltf transcription and secretion exacerbated neuronal ferroptosis by accumulating intraneuronal iron. Furthermore, the administration of recombinant Ltf protected against neuronal ferroptosis and improved neurobehavior in hyperglycemic ICH mice, and vice versa. These results indicate that supplementing Ltf or inhibiting neuronal ferroptosis are promising potential strategies to improve the acute outcomes of diabetic ICH in the clinic.

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Neutrophil infiltration and ICH prognosis are aggravated in hyperglycemic mice.

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Hyperglycemia impairs PPAR-γ activity and decreases Ltf expression in neutrophils.

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The lack of neutrophilic Ltf fails to decrease intraneuronal iron and ferroptosis.

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rLtf eases neuronal ferroptosis and neurologic deficits in hyperglycemic ICH mice.

Animal Models of Chorioamnionitis: Considerations for Translational Medicine

Preterm birth is defined as any birth occurring before 37 completed weeks of gestation by the World Health Organization. Preterm birth is responsible for perinatal mortality and long-term neurological morbidity. Acute chorioamnionitis is observed in 70% of premature labor and is associated with a heavy burden of multiorgan morbidities in the offspring. Unfortunately, chorioamnionitis is still missing effective biomarkers and early placento- as well as feto-protective and curative treatments. This review summarizes recent advances in the understanding of the underlying mechanisms of chorioamnionitis and subsequent impacts on the pregnancy outcome, both during and beyond gestation. This review also describes relevant and current animal models of chorioamnionitis used to decipher associated mechanisms and develop much needed therapies. Improved knowledge of the pathophysiological mechanisms underpinning chorioamnionitis based on preclinical models is a mandatory step to identify early in utero diagnostic biomarkers and design novel anti-inflammatory interventions to improve both maternal and fetal outcomes.

Inflammatory blockade prevents injury to the developing pulmonary gas exchange surface in preterm primates

Perinatal inflammatory stress is associated with early life morbidity and lifelong consequences for pulmonary health. Chorioamnionitis, an inflammatory condition affecting the placenta and fluid surrounding the developing fetus, affects 25 to 40% of preterm births. Severe chorioamnionitis with preterm birth is associated with significantly increased risk of pulmonary disease and secondary infections in childhood, suggesting that fetal inflammation may markedly alter the development of the lung. Here, we used intra-amniotic lipopolysaccharide (LPS) challenge to induce experimental chorioamnionitis in a prenatal rhesus macaque (Macaca mulatta) model that mirrors structural and temporal aspects of human lung development. Inflammatory injury directly disrupted the developing gas exchange surface of the primate lung, with extensive damage to alveolar structure, particularly the close association and coordinated differentiation of alveolar type 1 pneumocytes and specialized alveolar capillary endothelium. Single-cell RNA sequencing analysis defined a multicellular alveolar signaling niche driving alveologenesis that was extensively disrupted by perinatal inflammation, leading to a loss of gas exchange surface and alveolar simplification, with notable resemblance to chronic lung disease in newborns. Blockade of the inflammatory cytokines interleukin-1β and tumor necrosis factor-α ameliorated LPS-induced inflammatory lung injury by blunting stromal responses to inflammation and modulating innate immune activation in myeloid cells, restoring structural integrity and key signaling networks in the developing alveolus. These data provide new insight into the pathophysiology of developmental lung injury and suggest that modulating inflammation is a promising therapeutic approach to prevent fetal consequences of chorioamnionitis.

Evaluating the diagnosis and treatment of Chlamydia trachomatis and Neisseria gonorrhoeae in pregnant women to prevent adverse neonatal consequences in Gaborone, Botswana: protocol for the Maduo study

BACKGROUND

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are extremely common sexually transmitted infections (STIs) that are associated with adverse birth and neonatal outcomes, and the risk of vertical transmission of CT and NG during delivery is high. The majority of CT and NG infections are asymptomatic and missed by the standard of care in most countries (treatment based on symptoms). Thus, it is likely that missed maternal CT and NG infections contribute to preventable adverse health outcomes among women and children globally. This study aims to assess the effectiveness of CT and NG testing for asymptomatic pregnant women to prevent adverse neonatal outcomes, understand the inflammatory response linking CT and NG infections to adverse neonatal outcomes, and conduct an economic analysis of the CT and NG testing intervention.

METHODS

The Maduo ("results" in Setswana) is a prospective, cluster-controlled trial in Gaborone, Botswana to compare a near point-of-care CT and NG testing and treatment intervention implemented in "study clinics" with standard antenatal care (World Health Organization-endorsed "syndromic management" strategy based on signs and symptoms without laboratory confirmation) implemented in "standard of care clinics" among asymptomatic pregnant women. The primary outcome is vertical transmission of CT/NG infection. Secondary outcomes include preterm birth (delivery < 37 completed weeks of gestation) and/or low birth weight (< 2500 g). The trial will also evaluate immunological and inflammatory markers of adverse neonatal outcomes, as well as the costs and cost-effectiveness of the intervention compared with standard care.

DISCUSSION

The Maduo study will improve our understanding of the effectiveness and cost-effectiveness of CT and NG testing among asymptomatic pregnant women. It will also increase knowledge about the CT/NG-related immune responses that might drive adverse neonatal outcomes. Further, results from this study could encourage expansion of STI testing during antenatal care in low resource settings and improve maternal and neonatal health globally.

TRIAL REGISTRATION

This trial is registered with ClinicalTrials.gov (Identifier NCT04955717, First posted: July 9, 2021)).

Chorioamnionitis and neonatal outcomes

Chorioamnionitis or intrauterine inflammation is a frequent cause of preterm birth. Chorioamnionitis can affect almost every organ of the developing fetus. Multiple microbes have been implicated to cause chorioamnionitis, but "sterile" inflammation appears to be more common. Eradication of microorganisms has not been shown to prevent the morbidity and mortality associated with chorioamnionitis as inflammatory mediators account for continued fetal and maternal injury. Mounting evidence now supports the concept that the ensuing neonatal immune dysfunction reflects the effects of inflammation on immune programming during critical developmental windows, leading to chronic inflammatory disorders as well as vulnerability to infection after birth. A better understanding of microbiome alterations and inflammatory dysregulation may help develop better treatment strategies for infants born to mothers with chorioamnionitis.

A Systematic Review of the Safety of Blocking the IL-1 System in Human Pregnancy

Blockade of the interleukin-1 (IL-1) pathway has been used therapeutically in several inflammatory diseases including arthritis and cryopyrin-associated periodic syndrome (CAPS). These conditions frequently affect women of childbearing age and continued usage of IL-1 specific treatments throughout pregnancy has been reported. IL-1 is involved in pregnancy complications and its blockade could have therapeutic potential. We systematically reviewed all reported cases of IL-1 blockade in human pregnancy to assess safety and perinatal outcomes. We searched several databases to find reports of specific blockade of the IL-1 pathway at any stage of pregnancy, excluding broad spectrum or non-specific anti-inflammatory intervention. Our literature search generated 2439 references of which 22 studies included, following extensive review. From these, 88 different pregnancies were assessed. Most (64.8%) resulted in healthy term deliveries without any obstetrical/neonatal complications. Including pregnancy exposed to Anakinra or Canakinumab, 12 (15.0%) resulted in preterm birth and one stillbirth occurred. Regarding neonatal complications, 2 cases of renal agenesis (2.5%) were observed, and 6 infants were diagnosed with CAPS (7.5%). In conclusion, this systematic review describes that IL-1 blockade during pregnancy is not associated with increased adverse perinatal outcomes, considering that treated women all presented an inflammatory disease associated with elevated risk of pregnancy complications.

Fructooligosaccharide ameliorates high-fat induced intrauterine inflammation and improves lipid profile in the hamster offspring

Maternal high-fat diet (HFD) often results in intrauterine and feto-placental inflammation, and increases the risks of fetal programming of metabolic diseases. Intake of prebiotic is reported beneficial. However, its effects on HFD during pregnancy and lactation is not known. We evaluated the maternal intake of fructooligosaccharide (FOS) and its impact on placental inflammation, offspring's adiposity, glucose, and lipid metabolism in their later life. Female Golden Syrian hamsters were fed with a control diet (CD, 26.4 % energy from fat) or HFD (60.7% energy from fat) in the presence or absence of FOS from preconception until lactation. All pups were switched over to CD after lactation and continued until the end. Placental inflammation was upregulated in HFD-fed dam, as measured by a high concentration of hsCRP in the serum and amniotic fluid. Neutrophil infiltration was significantly increased in the decidua through the chorionic layer of the placenta. The expression of pro-inflammatory cytokines such as COX2, NFκβ, IL-8, TGFβ mRNA was increased in the chorioamniotic membrane (P <.05). The HFD/CD hamsters had more adiposity, higher triglyceride, and low HDL at 12 months of age compared to CD/CD (P <.05). However, HFD+FOS/CD-fed hamsters prevented adverse effects such as placental inflammation, neutrophil infiltration, glucose, and lipid profiles in the offspring (P <.05). Anti-inflammatory and lipid-lowering effects of FOS may reduce placental inflammation by lowering neutrophil infiltration and decreasing the production of pro-inflammatory cytokines. Intake of FOS during pregnancy may be beneficial in maintaining lipid metabolism and preventing excess adiposity for mother and their offspring.

IFNγ-Producing γ/δ T Cells Accumulate in the Fetal Brain Following Intrauterine Inflammation

Intrauterine inflammation impacts prenatal neurodevelopment and is linked to adverse neurobehavioral outcomes ranging from cerebral palsy to autism spectrum disorder. However, the mechanism by which a prenatal exposure to intrauterine inflammation contributes to life-long neurobehavioral consequences is unknown. To address this gap in knowledge, this study investigates how inflammation transverses across multiple anatomic compartments from the maternal reproductive tract to the fetal brain and what specific cell types in the fetal brain may cause long-term neuronal injury. Utilizing a well-established mouse model, we found that mid-gestation intrauterine inflammation resulted in a lasting neutrophil influx to the decidua in the absence of maternal systemic inflammation. Fetal immunologic changes were observed at 72-hours post-intrauterine inflammation, including elevated neutrophils and macrophages in the fetal liver, and increased granulocytes and activated microglia in the fetal brain. Through unbiased clustering, a population of Gr-1+ γ/δ T cells was identified as the earliest immune cell shift in the fetal brain of fetuses exposed to intrauterine inflammation and determined to be producing high levels of IFNγ when compared to γ/δ T cells in other compartments. In a case-control study of term infants, IFNγ was found to be elevated in the cord blood of term infants exposed to intrauterine inflammation compared to those without this exposure. Collectively, these data identify a novel cellular immune mechanism for fetal brain injury in the setting of intrauterine inflammation.

Elevated inflammatory mediators from the maternal-fetal interface to fetal circulation during labor

BACKGROUND

Elevated cytokines, like IL-1βand IL-6, are known to contribute to the pathogenesis of labor. However, the change of inflammatory mediators in maternal-fetal interface to fetal circulation is obscure.

STUDY DESIGN AND METHODS

We investigated the changes of inflammatory cytokines, chemokines and macrophage in maternal-fetal interface tissues and fetal circulation of women in labor vs. non-labor. Human myometrium, placenta, decidua, fetal membrane and umbilical blood were obtained from in-labor and non-in-labor women who eventually delivered live, singleton infants at term (>37 weeks gestation) by elective caesarean section. Luminex was used to measure the level of cytokines (TNF-α, IL-1β, IL-6, IL-8) and chemokines (MCP-1, GM-CSF, MIP-1α, MIP-1β) in each sample (tissue and umbilical blood). Macrophage infiltration was demonstrated by immunohistochemistry.

RESULTS

During labor, the level of cytokines TNF-α, IL-1β, IL-6 and IL-8 and chemokine MCP-1 and MIP-1β in myometrium is significantly higher (p < 0.05), than those obtained from non-laboring patients. This increase coincides with the influx of macrophage into the myometrium. In addition, IL-1β and IL-8 (p < 0.05) are also up regulated in fetal membrane during labor compared to non-labor. The cytokines do not change significantly in placenta and decidua tissue. In fetal circulation, IL-6 (p < 0.05) is up regulated in umbilical vein blood in labor group. IL-8 (p = 0.08) in umbilical vein also show an increasing trend during labor.

CONCLUSIONS

There are markedly elevated inflammatory mediators in maternal-fetal interface during labor. The increased maternal inflammatory factors released into the fetal circulation through placenta circulation at the time of labor. This increase coincides with the influx of macrophage into the pregnancy tissue, suggesting that the inflammatory response might play an important role in the onset of labor.

Necrotizing funisitis is an indicator that intra-amniotic inflammatory response is more severe and amnionitis is more frequent in the context of the extension of inflammation into Wharton's jelly

OBJECTIVE

Necrotizing funisitis (NF) is defined as the presence of an arc (i.e., crescent/band/ring/halos) of infiltrated neutrophils and/or associated debris in Wharton's jelly (WJ) of umbilical-cord (UC). However, no information exists about the comparison in intra-amniotic inflammatory-response (IAIR) and inflammation in extra-placental membranes between the presence and absence of NF in the context of inflammation in WJ among spontaneous preterm births (PTBs). The objective of current study is to examine this issue.

MATERIALS AND METHODS

We examined IAIR and the frequency of amnionitis according to the progression of inflammation in UC (i.e. stage-1, umbilical phlebitis [inflammation in umbilical-vein(UV)] only; stage-2, involvement of at least one umbilical-artery[UA] and either the other UA or UV without extension into WJ; stage-3, the extension of inflammation into WJ without NF; stage-4, the extension of inflammation into WJ with NF) in 120singleton spontaneous PTBs (<37weeks). IAIR was gauged by AF MMP-8 (ng/ml) within 3days before birth.

RESULTS

1) Stage-1, stage-2, stage-3, and stage-4 were present in 20%(24/120), 6%(7/120), 61%(73/120), and 13%(16/120) of cases respectively; 2) AF MMP-8 continuously increased (stage-1 vs. stage-2 vs. stage-3 vs. stage-4; median[ng/ml], range[ng/ml]; 207.2[16.8-1196.5] vs. 444.1[8.5-2608.0] vs. 458.8[0.4-3116.7] vs. 1859.7[912.3-5304.8]; Spearman's rank correlation-test, α = 0.454, P = 0.006), and the frequency of increased AF MMP-8 (≥854.1 ng/ml) elevated (stage-1 vs. stage-2 vs. stage-3 vs. stage-4; 13%[1/8] vs. 33%[1/3] vs. 32%[6/19] vs. 100%[5/5]; Linear-by-linear-association, P = 0.012) with the progression of inflammation in UC; 3) Moreover, there was a stepwise increase in the frequency of amnionitis according to the progression of inflammation in UC (stage-1, 33%[8/24]; stage-2, 43%[3/7]; stage-3, 62%[45/73]; stage-4, 81%[13/16]; Linear-by-linear-association, P = 0.001).

CONCLUSION

NF is an indicator that IAIR is more severe and amnionitis is more frequent in the context of the extension of inflammation into WJ. Therefore, current study confirms that NF is the most advanced stage in the progression of inflammation within UC.

Toll-like receptor signaling is changed in ovine lymph node during early pregnancy

Toll-like receptors (TLRs) participate in regulation of adaptive immune responses, and lymph nodes play key roles in the initiation of immune responses. There is a tolerance to the allogenic fetus during pregnancy, but it is unclear that expression of TLR signaling is in ovine lymph node during early pregnancy. In this study, lymph nodes were sampled from day 16 of nonpregnant ewes and days 13, 16, and 25 of pregnant ewes, and the expressions of TLR family (TLR2, TLR3, TLR4, TLR5 and TLR9), adaptor proteins, including myeloid differentiation primary-response protein 88 (MyD88), tumor necrosis factor receptor associated factor 6 (TRAF6), and interleukin-1-receptor-associated kinase 1 (IRAK1), were analyzed through real-time quantitative polymerase chain reaction, Western blot, and immunohistochemistry analysis. The results showed that mRNA and protein levels of TLR2, TLR3, TLR4, TRAF6, and MyD88 were upregulated in the maternal lymph node, but TLR5, TLR9, and IRAK1 were downregulated during early pregnancy. In addition, MyD88 protein was located in the subcapsular sinus and lymph sinuses. Therefore, it is suggested that early pregnancy induces changes in TLR signaling in maternal lymph node, which may be involved in regulation of maternal immune responses in sheep.

The induction of preterm labor in rhesus macaques is determined by the strength of immune response to intrauterine infection

Intrauterine infection/inflammation (IUI) is a major contributor to preterm labor (PTL). However, IUI does not invariably cause PTL. We hypothesized that quantitative and qualitative differences in immune response exist in subjects with or without PTL. To define the triggers for PTL, we developed rhesus macaque models of IUI driven by lipopolysaccharide (LPS) or live Escherichia coli. PTL did not occur in LPS challenged rhesus macaques, while E. coli–infected animals frequently delivered preterm. Although LPS and live E. coli both caused immune cell infiltration, E. coli–infected animals showed higher levels of inflammatory mediators, particularly interleukin 6 (IL-6) and prostaglandins, in the chorioamnion-decidua and amniotic fluid (AF). Neutrophil infiltration in the chorio-decidua was a common feature to both LPS and E. coli. However, neutrophilic infiltration and IL6 and PTGS2 expression in the amnion was specifically induced by live E. coli. RNA sequencing (RNA-seq) analysis of fetal membranes revealed that specific pathways involved in augmentation of inflammation including type I interferon (IFN) response, chemotaxis, sumoylation, and iron homeostasis were up-regulated in the E. coli group compared to the LPS group. Our data suggest that the intensity of the host immune response to IUI may determine susceptibility to PTL.

Uterine Notch2 facilitates pregnancy recognition and corpus luteum maintenance via upregulating decidual Prl8a2

The maternal recognition of pregnancy is a necessary prerequisite for gestation maintenance through prolonging the corpus luteum lifespan and ensuring progesterone production. In addition to pituitary prolactin and placental lactogens, decidual derived prolactin family members have been presumed to possess luteotropic effect. However, there was a lack of convincing evidence to support this hypothesis. Here, we unveiled an essential role of uterine Notch2 in pregnancy recognition and corpus luteum maintenance. Uterine-specific deletion of Notch2 did not affect female fertility. Nevertheless, the expression of decidual Prl8a2, a member of the prolactin family, was downregulated due to Notch2 ablation. Subsequently, we interrupted pituitary prolactin function to determine the luteotropic role of the decidua by employing the lipopolysaccharide-induced prolactin resistance model, or blocking the prolactin signaling by prolactin receptor-Fc fusion protein, or repressing pituitary prolactin release by dopamine receptor agonist bromocriptine, and found that Notch2-deficient females were more sensitive to these stresses and ended up in pregnancy loss resulting from abnormal corpus luteum function and insufficient serum progesterone level. Overexpression of Prl8a2 in Notch2 knockout mice rescued lipopolysaccharide-induced abortion, highlighting its luteotropic function. Further investigation adopting Rbpj knockout and DNMAML overexpression mouse models along with chromatin immunoprecipitation assay and luciferase analysis confirmed that Prl8a2 was regulated by the canonical Notch signaling. Collectively, our findings demonstrated that decidual prolactin members, under the control of uterine Notch signaling, assisted pituitary prolactin to sustain corpus luteum function and serum progesterone level during post-implantation phase, which was conducive to pregnancy recognition and maintenance.

Progesterone secreted from the corpus luteum in the ovary is indispensable to pregnancy maintenance in both rodents and humans. Therefore, prolonged corpus luteum lifespan and sustainable progesterone production is a prerequisite for a successful pregnancy. In rodents, in addition to pituitary prolactin and placental lactogens, decidual derived factors have been presumed to possess luteotropic effects during the post-implantation stage. In this study, utilizing a mouse model with uterine specific deletion of Notch2, which displayed decreased level of decidual prolactin member Prl8a2, combined with multiple approaches to interrupt the pituitary prolactin signal, we demonstrated that decidual derived Prl8a2 assisted pituitary prolactin to sustain corpus luteum function and serum progesterone level during post-implantation phase, which was conducive to pregnancy recognition and maintenance. In addition, the expression of decidual Prl8a2 was under the direct control of the canonical Notch pathway. Together, we herein provide convincing evidence that decidual produced Prl8a2, modulated by uterine canonical Notch signaling, exhibits luteotropic functions and contributes to pregnancy maintenance.

Moderately pathogenic maternal influenza A virus infection disrupts placental integrity but spares the fetal brain

Maternal infection during pregnancy is a known risk factor for offspring mental health disorders. Animal models of maternal immune activation (MIA) have implicated specific cellular and molecular etiologies of psychiatric illness, but most rely on pathogen mimetics. Here, we developed a mouse model of live H3N2 influenza A virus (IAV) infection during pregnancy that induces a robust inflammatory response but is sublethal to both dams and offspring. We observed classic indicators of lung inflammation and severely diminished weight gain in IAV-infected dams. This was accompanied by immune cell infiltration in the placenta and partial breakdown of placental integrity. However, indications of fetal neuroinflammation were absent. Further hallmarks of mimetic-induced MIA, including enhanced circulating maternal IL-17A, were also absent. Respiratory IAV infection did result in an upregulation in intestinal expression of transcription factor RORγt, master regulator of a subset of T lymphocytes, TH17 cells, which are heavily implicated in MIA-induced etiologies. Nonetheless, subsequent augmentation in IL-17A production and concomitant overt intestinal injury was not evident. Our results suggest that mild or moderately pathogenic IAV infection during pregnancy does not inflame the developing fetal brain, and highlight the importance of live pathogen infection models for the study of MIA.

Understanding Host-Pathogen Interactions in Acute Chorioamnionitis Through the Use of Animal Models

Inflammation of the chorion and/or amnion during pregnancy is called chorioamnionitis. Acute chorioamnionitis is implicated in approximately 40% of preterm births and has wide-ranging implications for the mother, fetus, and newborn. Large disease burden and lack of therapeutic approaches drive the discovery programs to define and test targets to tackle chorioamnionitis. Central to the advancement of these studies is the use of animal models. These models are necessary to deepen our understanding of basic mechanisms of host-pathogen interactions central to chorioamnionitis disease pathogenesis. Models of chorioamnionitis have been developed in numerous species, including mice, rabbits, sheep, and non-human primates. The various models present an array of strategies for initiating an inflammatory response and unique opportunities for studying its downstream consequences for mother, fetus, or newborn. In this review, we present a discussion of the key features of human chorioamnionitis followed by evaluation of currently available animal models in light of these features and consideration of how these models can be best applied to tackle outstanding questions in the field.

Transcriptomic analysis of equine chorioallantois reveals immune networks and molecular mechanisms involved in nocardioform placentitis

Nocardioform placentitis (NP) continues to result in episodic outbreaks of abortion and preterm birth in mares and remains a poorly understood disease. The objective of this study was to characterize the transcriptome of the chorioallantois (CA) of mares with NP. The CA were collected from mares with confirmed NP based upon histopathology, microbiological culture and PCR for Amycolatopsis spp. Samples were collected from the margin of the NP lesion (NPL, n = 4) and grossly normal region (NPN, n = 4). Additionally, CA samples were collected from normal postpartum mares (Control; CRL, n = 4). Transcriptome analysis identified 2892 differentially expressed genes (DEGs) in NPL vs. CRL and 2450 DEGs in NPL vs. NPN. Functional genomics analysis elucidated that inflammatory signaling, toll-like receptor signaling, inflammasome activation, chemotaxis, and apoptosis pathways are involved in NP. The increased leukocytic infiltration in NPL was associated with the upregulation of matrix metalloproteinase (MMP1, MMP3, and MMP8) and apoptosis-related genes, such as caspases (CASP3 and CASP7), which could explain placental separation associated with NP. Also, NP was associated with downregulation of several placenta-regulatory genes (ABCG2, GCM1, EPAS1, and NR3C1), angiogenesis-related genes (VEGFA, FLT1, KDR, and ANGPT2), and glucose transporter coding genes (GLUT1, GLUT10, and GLUT12), as well as upregulation of hypoxia-related genes (HIF1A and EGLN3), which could elucidate placental insufficiency accompanying NP. In conclusion, our findings revealed for the first time, the key regulators and mechanisms underlying placental inflammation, separation, and insufficiency during NP, which might lead to the development of efficacious therapies or diagnostic aids by targeting the key molecular pathways.

The amniotic fluid cell-free transcriptome in spontaneous preterm labor

The amniotic fluid (AF) cell-free RNA was shown to reflect physiological and pathological processes in pregnancy, but its value in the prediction of spontaneous preterm delivery is unknown. Herein we profiled cell-free RNA in AF samples collected from women who underwent transabdominal amniocentesis after an episode of spontaneous preterm labor and subsequently delivered within 24 h (n = 10) or later (n = 28) in gestation. Expression of known placental single-cell RNA-Seq signatures was quantified in AF cell-free RNA and compared between the groups. Random forest models were applied to predict time-to-delivery after amniocentesis. There were 2385 genes differentially expressed in AF samples of women who delivered within 24 h of amniocentesis compared to gestational age-matched samples from women who delivered after 24 h of amniocentesis. Genes with cell-free RNA changes were associated with immune and inflammatory processes related to the onset of labor, and the expression of placental single-cell RNA-Seq signatures of immune cells was increased with imminent delivery. AF transcriptomic prediction models captured these effects and predicted delivery within 24 h of amniocentesis (AUROC = 0.81). These results may inform the development of biomarkers for spontaneous preterm birth.

Landscape of Preterm Birth Therapeutics and a Path Forward

Preterm birth (PTB) remains the leading cause of infant morbidity and mortality. Despite 50 years of research, therapeutic options are limited and many lack clear efficacy. Tocolytic agents are drugs that briefly delay PTB, typically to allow antenatal corticosteroid administration for accelerating fetal lung maturity or to transfer patients to high-level care facilities. Globally, there is an unmet need for better tocolytic agents, particularly in low- and middle-income countries. Although most tocolytics, such as betamimetics and indomethacin, suppress downstream mediators of the parturition pathway, newer therapeutics are being designed to selectively target inflammatory checkpoints with the goal of providing broader and more effective tocolysis. However, the relatively small market for new PTB therapeutics and formidable regulatory hurdles have led to minimal pharmaceutical interest and a stagnant drug pipeline. In this review, we present the current landscape of PTB therapeutics, assessing the history of drug development, mechanisms of action, adverse effects, and the updated literature on drug efficacy. We also review the regulatory hurdles and other obstacles impairing novel tocolytic development. Ultimately, we present possible steps to expedite drug development and meet the growing need for effective preterm birth therapeutics.

Neutrophil to Lymphocyte Ratio in Maternal Blood: A Clue to Suspect Amnionitis

There is no information about whether maternal neutrophil to lymphocyte ratios (NLRs) progressively increase with respect to the progression of acute histologic chorioamnionitis (acute-HCA) and increased maternal NLR is a risk factor for amnionitis, known as advanced acute-HCA, in pregnant women at risk for spontaneous preterm birth (PTB). The objective of the current study is to examine this issue. The study population included 132 singleton PTB (<34 weeks) due to either preterm labor or preterm-PROM with both placental pathology and maternal CBC results within 48 h before delivery. We examined maternal NLRs according to the progression of acute-HCA in extra-placental membranes (EPM) (i.e., group-0, inflammation-free EPM; group-1, inflammation restricted to decidua; group-2, inflammation restricted to the membranous trophoblast of chorion and the decidua; group-3, inflammation in the connective tissue of chorion but not amnion; group-4, amnionitis). Maternal NLRs significantly and progressively increased with the progression of acute-HCA (Spearman’s rank correlation test, γ = 0.363, p = 0.000019). Moreover, the increased maternal NLR (≥7.75) (Odds-ratio 5.56, 95% confidence-interval 1.26-24.62, p < 0.05) was a significant independent risk factor for amnionitis even after the correction for potential confounders. In conclusion, maternal NLRs significantly and progressively increased according to the progression of acute-HCA and the increased maternal NLR (≥7.75) was an independent risk factor for amnionitis in spontaneous PTB. The evaluation of the performance of NLR should clearly require a prospective description of this parameter in a cohort of patients with either threatened PTL or preterm-PROM.

The Rhesus Macaque Serves As a Model for Human Lateral Branch Nephrogenesis

BACKGROUND

Most nephrons are added in late gestation. Truncated extrauterine nephrogenesis in premature infants results in fewer nephrons and significantly increased risk for CKD in adulthood. To overcome the ethical and technical difficulties associated with studies of late-gestation human fetal kidney development, third-trimester rhesus macaques served as a model to understand lateral branch nephrogenesis (LBN) at the molecular level.

METHODS

Immunostaining and 3D rendering assessed morphology. Single-cell (sc) and single-nucleus (sn) RNA-Seq were performed on four cortically enriched fetal rhesus kidneys of 129-131 days gestational age (GA). An integrative bioinformatics strategy was applied across single-cell modalities, species, and time. RNAScope validation studies were performed on human archival tissue.

RESULTS

Third-trimester rhesus kidney undergoes human-like LBN. scRNA-Seq of 23,608 cells revealed 37 transcriptionally distinct cell populations, including naïve nephron progenitor cells (NPCs), with the prior noted marker genes CITED1, MEOX1, and EYA1 (c25). These same populations and markers were reflected in snRNA-Seq of 5972 nuclei. Late-gestation rhesus NPC markers resembled late-gestation murine NPC, whereas early second-trimester human NPC markers aligned to midgestation murine NPCs. New, age-specific rhesus NPCs (SHISA8) and ureteric buds (POU3F4 and TWIST) predicted markers were verified in late-gestation human archival samples.

CONCLUSIONS

Rhesus macaque is the first model of bona fide LBN, enabling molecular studies of late gestation, human-like nephrogenesis. These molecular findings support the hypothesis that aging nephron progenitors have a distinct molecular signature and align to their earlier human counterparts, with unique markers highlighting LBN-specific progenitor maturation.

RNA Sequencing Reveals Distinct Immune Responses in the Chorioamniotic Membranes of Women with Preterm Labor and Microbial or Sterile Intra-amniotic Inflammation

Preterm labor precedes premature birth, the leading cause of neonatal morbidity and mortality worldwide. Preterm labor can occur in the context of either microbe-associated intra-amniotic inflammation (i.e., intra-amniotic infection) or intra-amniotic inflammation in the absence of detectable microorganisms (i.e., sterile intra-amniotic inflammation). Both intra-amniotic infection and sterile intra-amniotic inflammation trigger local immune responses that have deleterious effects on fetal life. Yet, the extent of such immune responses in the fetal tissues surrounding the amniotic cavity (i.e., the chorioamniotic membranes) is poorly understood. By using RNA sequencing (RNA seq) as a discovery approach, we found that there were significant transcriptomic differences involving host response to pathogens in the chorioamniotic membranes of women with intra-amniotic infection compared to those from women without inflammation. In addition, the sterile or microbial nature of intra-amniotic inflammation was associated with distinct transcriptomic profiles in the chorioamniotic membranes. Moreover, the immune response in the chorioamniotic membranes of women with sterile intra-amniotic inflammation was milder in nature than that induced by microbes and involved the upregulation of alarmins and inflammasome-related molecules. Lastly, the presence of maternal and fetal inflammatory responses in the placenta was associated with the upregulation of immune processes in the chorioamniotic membranes. Collectively, these findings provide insight into the immune responses against microbes or alarmins that take place in the fetal tissues surrounding the amniotic cavity, shedding light on the immunobiology of preterm labor and birth.

Polymicrobial stimulation of human fetal membranes induce neutrophil activation and neutrophil extracellular trap release

Preterm birth is a major contributor to neonatal mortality and morbidity. While the causes of preterm birth remain incompletely understood, infection is a major risk factor, and chorioamnionitis is commonly observed. Chorioamnionitis is characterized by inflammation and neutrophil infiltration of the fetal membranes (FM). We recently reported that human FMs which had been exposed to low levels of bacterial lipopolysaccharide (LPS) recruit neutrophils and activate them, increasing their secretion of pro-inflammatory cytokines, degranulation of myeloperoxidase (MPO), and release of neutrophil extracellular traps (NETs). Herein, we demonstrate that conditioned media (CM) from viral dsRNA (Poly(I:C))-stimulated FMs also increased neutrophil migration, and induced the secretion of inflammatory IL-8 and the release of NETs. Furthermore, CM from FMs stimulated by a combination of bacterial LPS and Poly(I:C) augmented neutrophil NET release, compared to CM from FMs stimulated with either Poly(I:C) or LPS alone. NETs induced by FMs exposed to Poly(I:C), with or without LPS, were released and degraded quicker than those induced by resting or LPS-stimulated FM-CM. These findings indicate that FMs exposed to viral dsRNA promote neutrophil recruitment, activation and NET formation, similar to FMs exposed to bacterial LPS alone. However, in response to FM polymicrobial stimulation the levels and kinetics of NET release are augmented. This work builds upon our understanding of how infections at the maternal-fetal interface may affect neutrophil function.

Streptococcus pyogenes infects human endometrium by limiting the innate immune response

Group A Streptococcus (GAS), a Gram-positive human-specific pathogen, yields 517,000 deaths annually worldwide, including 163,000 due to invasive infections and among them puerperal fever. Before efficient prophylactic measures were introduced, the mortality rate for mothers during childbirth was approximately 10%; puerperal fever still accounts for over 75,000 maternal deaths annually. Yet, little is known regarding the factors and mechanisms of GAS invasion and establishment in postpartum infection. We characterized the early steps of infection in an ex vivo infection model of the human decidua, the puerperal fever portal of entry. Coordinate analysis of GAS behavior and the immune response led us to demonstrate that (a) GAS growth was stimulated by tissue products; (b) GAS invaded tissue and killed approximately 50% of host cells within 2 hours, and these processes required SpeB protease and streptolysin O (SLO) activities, respectively; and (c) GAS impaired the tissue immune response. Immune impairment occurred both at the RNA level, with only partial induction of the innate immune response, and protein level, in an SLO- and SpeB-dependent manner. Our study indicates that efficient GAS invasion of the decidua and the restricted host immune response favored its propensity to develop rapid invasive infections in a gynecological-obstetrical context.

Activated Neutrophils Propagate Fetal Membrane Inflammation and Weakening through ERK and Neutrophil Extracellular Trap-Induced TLR-9 Signaling

Preterm birth is associated with significant neonatal mortality and morbidity worldwide. Chorioamnionitis, inflammation of the fetal membranes (FMs), is a major risk factor and is characterized by neutrophil infiltration. However, the role of neutrophils at the FMs remains unclear. We recently reported that FMs exposed to bacterial LPS recruited more neutrophils compared with resting FMs and activated them to degranulate and release reactive oxygen species, chemokines/cytokines, and neutrophil extracellular traps. We posit that under resting conditions, neutrophils play a protective surveillance role, whereas during infection/inflammation, they induce FM tissue injury. To test this, human FM explants were exposed to neutrophil conditioned media (CM). We demonstrate that CM from neutrophils exposed to resting FM-CM did not affect FM viability or function. Conversely, CM from neutrophils activated by LPS-stimulated FM-CM significantly increased FM secretion of inflammatory IL-6, IL-8, GRO-α, and the markers of membrane weakening, MMP-9 and PGE₂ This FM response was partially mediated by ERK signaling and neutrophil extracellular traps through the activation of the DNA sensor, TLR-9. Thus, neutrophils recruited by FMs during infection can propagate FM inflammation and weakening, acting in a feed-forward mechanism to propagate tissue injury at the maternal-fetal interface, increasing the risk of premature FM rupture and preterm birth in women with intrauterine infection.

Prenatal inflammation enhances antenatal corticosteroid-induced fetal lung maturation

Respiratory complicˆations are the major cause of morbidity and mortality among preterm infants, which is partially prevented by the administration of antenatal corticosteroids (ACS). Most very preterm infants are exposed to chorioamnionitis, but short- and long-term effects of ACS treatment in this setting are not well defined. In low-resource settings, ACS increased neonatal mortality by perhaps increasing infection. We report that treatment with low-dose ACS in the setting of inflammation induced by intraamniotic lipopolysaccharide (LPS) in rhesus macaques improves lung compliance and increases surfactant production relative to either exposure alone. RNA sequencing shows that these changes are mediated by suppression of proliferation and induction of mesenchymal cellular death via TP53. The combined exposure results in a mature-like transcriptomic profile with inhibition of extracellular matrix development by suppression of collagen genes COL1A1, COL1A2, and COL3A1 and regulators of lung development FGF9 and FGF10. ACS and inflammation also suppressed signature genes associated with proliferative mesenchymal progenitors similar to the term gestation lung. Treatment with ACS in the setting of inflammation may result in early respiratory advantage to preterm infants, but this advantage may come at a risk of abnormal extracellular matrix development, which may be associated with increased risk of chronic lung disease.

Unique maternal immune and functional microbial profiles during prenatal stress

Maternal stress during pregnancy is widespread and is associated with poor offspring outcomes, including long-term mental health issues. Prenatal stress-induced fetal neuroinflammation is thought to underlie aberrant neurodevelopment and to derive from a disruption in intrauterine immune homeostasis, though the exact origins are incompletely defined. We aimed to identify divergent immune and microbial metagenome profiles of stressed gestating mice that may trigger detrimental inflammatory signaling at the maternal-fetal interface. In response to stress, maternal glucocorticoid circuit activation corresponded with indicators of systemic immunosuppression. At the maternal-fetal interface, density of placental mononuclear leukocytes decreased with stress, yet maternal whole blood leukocyte analysis indicated monocytosis and classical M1 phenotypic shifts. Genome-resolved microbial metagenomic analyses revealed reductions in genes, microbial strains, and metabolic pathways in stressed dams that are primarily associated with pro-inflammatory function. In particular, disrupted Parasutterella excrementihominis appears to be integral to inflammatory and metabolic dysregulation during prenatal stress. Overall, these perturbations in maternal immunological and microbial regulation during pregnancy may displace immune equilibrium at the maternal-fetal interface. Notably, the absence of and reduction in overt maternal inflammation during stress indicates that the signaling patterns driving fetal outcomes in this context are more nuanced and complex than originally anticipated.

Transcriptomic analysis of equine placenta reveals key regulators and pathways involved in ascending placentitis†

Improved understanding of the molecular mechanisms underlying ascending equine placentitis holds the potential for the development of new diagnostic tools and therapies to forestall placentitis-induced preterm labor. The current study characterized the equine placental transcriptome (chorioallantois [CA] and endometrium [EN]) during placentitis (placentitis group, n = 6) in comparison to gestationally-matched controls (control group, n = 6). Transcriptome analysis identified 2953 and 805 differentially expressed genes in CA and EN during placentitis, respectively. Upstream regulator analysis revealed the central role of toll-like receptors (TLRs) in triggering the inflammatory signaling, and consequent immune-cell chemotaxis. Placentitis was associated with the upregulation of matrix metalloproteinase (MMP1, MMP2, and MMP9) and apoptosis-related genes such as caspases (CASP3, CASP4, and CASP7) in CA. Also, placentitis was associated with downregulation of transcripts coding for proteins essential for placental steroidogenesis (SRD5A1 and AKR1C1), progestin signaling (PGRMC1 and PXR) angiogenesis (VEGFA, VEGFR2, and VEGFR3), and nutrient transport (GLUT12 and SLC1A4), as well as upregulation of hypoxia-related genes (HIF1A and EGLN3), which could explain placental insufficiency during placentitis. Placentitis was also associated with aberrant expression of several placenta-regulatory genes, such as PLAC8, PAPPA, LGALS1, ABCG2, GCM1, and TEPP, which could negatively affect placental functions. In conclusion, our findings revealed for the first time the key regulators and mechanisms underlying placental inflammation, separation, and insufficiency during equine placentitis, which might lead to the development of efficacious therapies or diagnostic aids by targeting the key molecular pathways.

Human Decidual Stromal Cells in Early Pregnancy Induce Functional Re-Programming of Monocyte-Derived Dendritic Cells via Crosstalk Between G-CSF and IL-1β

Accumulation of dendritic cells (DCs) is a special characteristic of the decidual microenvironment. Decidua-infiltrated DCs show unique phenotypes and functions that promote the establishment of fetal-maternal tolerance. However, the regulatory mechanisms yet to be fully investigated. Decidual stromal cells (DSCs) are the major cellular component of decidua tissue. The interactions between DSCs and decidua-infiltrated immunocytes dictate immune tolerance in early pregnancy. Therefore, in the present study, we explore the effect of early pregnancy DSCs on monocyte-derived DCs and the relevant mechanisms. DSC-conditioned DCs showed altered phenotypes, secretion profiles and Th2 priming potential. G-CSF concentration was significantly up-regulated in the co-culture supernatant between DSCs and DCs. Supplementation of G-CSF neutralizing antibody partly reversed the reprogramming of DCs mediated by DSCs. Furthermore, G-CSF production was promoted by IL-1β, which was mainly produced by DCs and significantly up-regulated after their cultivation with DSCs. Interestingly, the effects of DSC on IL-1β production of DCs occurred in their immature stage but not their mature stage. Lastly, no significant difference of G-CSF was found in DSCs from healthy early pregnancy women and spontaneous abortions (SA) patients. However, DSCs from SA patients secreted less G-CSF in response to exogenous rhIL-1β or DC cultivation. In conclusion, our study bolster the understanding of the decidual immunomodulatory microenvironment during early pregnancy, and brings new insight into the potential clinical value of G-CSF in pregnancy disorders.

NLRP3 inflammasome function and pyroptotic cell death in human placental Hofbauer cells

Alterations in the number and protein/gene expression of Hofbauer cells (HBCs) may play a role in microbial-driven/cytokine-mediated placental inflammation, and in subsequent pregnancy complications such as villitis, histologic chorioamnionitis, and the fetal inflammatory response syndrome. Pyroptosis is an inflammatory form of cell death mediated by the inflammasome, a multi-protein complex which drives the processing and secretion of interleukin 1 beta (IL-1β). Pyroptosis can be triggered by bacterial lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in non-placental macrophages through activation of the NLRP3 inflammasome. However, the role of inflammasome activation and pyroptosis in HBC pathophysiology remains unclear. HBCs isolated from human term placentas were treated with or without LPS or ATP, alone or in combination. Treatment of HBCs with both LPS and ATP induced the rapid secretion of high levels of IL-1β and at the same time, cell death associated with nuclear condensation and cellular swelling. HBC treatment with both LPS and ATP induced caspase-1 activation, gasdermin D (GSDMD) cleavage, which mediates pyroptosis, and IL-1β processing. Caspase-1 activation, GSDMD cleavage, IL-1β processing, and IL-1β secretion were all significantly reduced following NLRP3 knockdown; inhibition of caspase-1; and inhibition of P2X7, the receptor that mediates K⁺ efflux. Together, our data indicate that LPS and ATP treatment stimulated NLRP3 inflammasome activation and pyroptosis in HBCs leading to the rapid release of IL-1β. Since the localization of HBCs confers a unique ability to influence microbial-associated placental and fetal inflammation, these studies suggest a key role for the inflammasome and pyroptosis in mediating HBC driven inflammation.