Viral infection of the placenta leads to fetal inflammation and sensitization to bacterial products predisposing to preterm labor

High-Throughput 3D-Printed Model of the Feto-Maternal Interface for the Discovery and Development of Preterm Birth Therapies

Spontaneous preterm birth (PTB) affects around 11% of births, posing significant risks to neonatal health due to the inflammation at the fetal-maternal interface (FMi). This inflammation disrupts immune tolerance during pregnancy, often leading to PTB. While organ-on-a-chip (OOC) devices effectively mimic the physiology, pathophysiology, and responses of FMi, their relatively low throughput limits their utility in high-throughput testing applications. To overcome this, we developed a three-dimensional (3D)-printed model that fits in a well of a 96-well plate and can be mass-produced while also accurately replicating FMi, enabling efficient screening of drugs targeting FMi inflammation. Our model features two cell culture chambers (maternal and fetal cells) interlinked via an array of microfluidic channels. It was thoroughly validated, ensuring cell viability, metabolic activity, and cell-specific markers. The maternal chamber was exposed to lipopolysaccharides (LPS) to induce an inflammatory state, and proinflammatory cytokines in the culture supernatant were quantified. Furthermore, the efficacy of anti-inflammatory inhibitors in mitigating LPS-induced inflammation was investigated. Results demonstrated that our model supports robust cell growth, maintains viability, and accurately mimics PTB-associated inflammation. This high-throughput 3D-printed model offers a versatile platform for drug screening, promising advancements in drug discovery and PTB prevention.

Association between maternal and perinatal outcomes and histological changes in the placenta of patients with Covid-19: A cohort study

Although studies evaluated placental involvement in Covid-19 patients, few have assessed its association with clinical repercussions. The study aimed to determine the association between the clinical status and maternal and perinatal outcomes of patients with Covid-19 at delivery and changes in placental histology. It is so far the largest cohort evaluating placentas of patients infected by the SARS-CoV-2. A secondary analysis was conducted of a database from which a cohort of 226 patients, who tested real-time polymerase chain reaction-positive for Covid-19 at delivery and whose placentas were collected and submitted to pathology, was selected for inclusion. One or more types of histological changes were detected in 44.7% of the 226 placentas evaluated. The most common abnormalities were maternal vascular malperfusion (38%), evidence of inflammation/infection (9.3%), fetal vascular malperfusion (0.8%), fibrinoid changes and intervillous thrombi (0.4%). Oxygen use (P = .01) and need for admission to an intensive care unit (ICU) (P = .04) were less common in patients with placental findings, and hospital stay was shorter in these patients (P = .04). There were more fetal deaths among patients with evidence of inflammation/infection (P = .02). Fetal death, albeit uncommon, is associated with findings of inflammation/infection. Oxygen use and need for admission to an ICU were less common among patients with placental findings, probably due to the pregnancy being interrupted early. None of the other findings was associated with maternal clinical status or with adverse perinatal outcome.

Palmitate and group B Streptococcus synergistically and differentially induce IL-1β from human gestational membranes

Introduction

Rupture of the gestational membranes often precedes major pregnancy complications, including preterm labor and preterm birth. One major cause of inflammation in the gestational membranes, chorioamnionitis (CAM) is often a result of bacterial infection. The commensal bacterium Streptococcus agalactiae, or Group B Streptococcus (GBS) is a leading infectious cause of CAM. Obesity is on the rise worldwide and roughly 1 in 4 pregnancy complications is related to obesity, and individuals with obesity are also more likely to be colonized by GBS. The gestational membranes are comprised of several distinct cell layers which are, from outermost to innermost: maternally-derived decidual stromal cells (DSCs), fetal cytotrophoblasts (CTBs), fetal mesenchymal cells, and fetal amnion epithelial cells (AECs). In addition, the gestational membranes have several immune cell populations; macrophages are the most common phagocyte. Here we characterize the effects of palmitate, the most common long-chain saturated fatty acid, on the inflammatory response of each layer of the gestational membranes when infected with GBS, using human cell lines and primary human tissue.

Results

Palmitate itself slightly but significantly augments GBS proliferation. Palmitate and GBS co-stimulation synergized to induce many inflammatory proteins and cytokines, particularly IL-1β and matrix metalloproteinase 9 from DSCs, CTBs, and macrophages, but not from AECs. Many of these findings are recapitulated when treating cells with palmitate and a TLR2 or TLR4 agonist, suggesting broad applicability of palmitate-pathogen synergy. Co-culture of macrophages with DSCs or CTBs, upon co-stimulation with GBS and palmitate, resulted in increased inflammatory responses, contrary to previous work in the absence of palmitate. In whole gestational membrane biopsies, the amnion layer appeared to dampen immune responses from the DSC and CTB layers (the choriodecidua) to GBS and palmitate co-stimulation. Addition of the monounsaturated fatty acid oleate, the most abundant monounsaturated fatty acid in circulation, dampened the proinflammatory effect of palmitate.

Discussion

These studies reveal a complex interplay between the immunological response of the distinct layers of the gestational membrane to GBS infection and that such responses can be altered by exposure to long-chain saturated fatty acids. These data provide insight into how metabolic syndromes such as obesity might contribute to an increased risk for GBS disease during pregnancy.

A Microphysiological Model to Mimic the Placental Remodeling during Early Stage of Pregnancy under Hypoxia-Induced Trophoblast Invasion

Placental trophoblast invasion is critical for establishing the maternal-fetal interface, yet the mechanisms driving trophoblast-induced maternal arterial remodeling remain elusive. To address this gap, we developed a three-dimensional microfluidic placenta-on-chip model that mimics early pregnancy placentation in a hypoxic environment. By studying human umbilical vein endothelial cells (HUVECs) under oxygen-deprived conditions upon trophoblast invasion, we observed significant HUVEC artery remodeling, suggesting the critical role of hypoxia in placentation. In particular, we found that trophoblasts secrete matrix metalloproteinase (MMP) proteins under hypoxic conditions, which contribute to arterial remodeling by the degradation of extracellular matrix components. This MMP-mediated remodeling is critical for facilitating trophoblast invasion and proper establishment of the maternal-fetal interface. In addition, our platform allows real-time monitoring of HUVEC vessel contraction during trophoblast interaction, providing valuable insights into the dynamic interplay between trophoblasts and maternal vasculature. Collectively, our findings highlight the importance of MMP-mediated arterial remodeling in placental development and underscore the potential of our platform to study pregnancy-related complications and evaluate therapeutic interventions.

Association between the COVID-19 pandemic and childhood development aged 30 to 36 months in South Korea, based on the National health screening program for infants and children database

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on the neurodevelopment of children. However, the precise effects of the virus and the social consequences of the pandemic on pediatric neurodevelopment are not yet fully understood. We aimed to compare the neurodevelopment of children between before and during the COVID-19 pandemic, as well as examine the impact of socioeconomic status (SES) and regional differences on the development.

METHODS

The study used the Korean Developmental Screening Test to compare the difference in the risk of neurodevelopmental delay between before and during the COVID-19 pandemic. Multivariable logistic regression analysis was conducted to identify the relationship between experiencing the COVID-19 pandemic and the risk of neurodevelopmental delay. Stratified analyses were performed to determine whether the developmental delays caused by the pandemic's impact varied depending on SES or regional inequality.

RESULTS

This study found an association between the experience of COVID-19 and a higher risk of neurodevelopmental delay in communication (adjusted OR [aOR]: 1.21, 95% confidence interval [CI]: 1.19, 1.22; P-value: < 0.0001) and social interaction (aOR: 1.15, 95% CI: 1.13, 1.17; P-value: < 0.0001) domains among children of 30-36 months' ages. Notably, the observed association in the Medicaid group of children indicates a higher risk of neurodevelopmental delay compared to those in the non-Medicaid group.

CONCLUSIONS

These findings highlight the need to be concerned about the neurodevelopment of children who experienced the COVID-19 pandemic. The study also calls for increased training and support for Medicaid children, parents, teachers, and healthcare practitioners. Additionally, policy programs focused on groups vulnerable to developmental delays are required.

Are innate lymphoid cells friend or foe in human pregnancy?

Innate lymphoid cells (ILCs) are involved in the innate immune system because they lack specific antigen receptors and lineage markers. ILCs also display phenotypic and characteristic features of adaptive immune cells. Therefore, ILCs are functional in essential interactions between adaptive and innate immunity. ILCs are found in both lymphoid and nonlymphoid tissues and migrate to the area of inflammation during the inflammatory process. ILCs respond to pathogens by producing a variety of cytokines and are involved in the barrier defense of antigens and in many immunological processes such as allergic events. Recent research has shown that ILCs are functional during human pregnancy and have been suggested to be essential for the healthy progression of pregnancy. In this review, we focus on the role of ILCs in human pregnancy by discussing the relationship between ILCs and the pregnancy microenvironment, specifically summarizing the role of ILCs in physiological and pathological pregnancies.

Zika virus co-opts microRNA networks to persist in placental niches detected by spatial transcriptomics

BACKGROUND

Zika virus congenital infection evades double-stranded RNA detection and may persist in the placenta for the duration of pregnancy without accompanying overt histopathologic inflammation. Understanding how viruses can persist and replicate in the placenta without causing overt cellular or tissue damage is fundamental to deciphering mechanisms of maternal-fetal vertical transmission.

OBJECTIVE

Placenta-specific microRNAs are believed to be a tenet of viral resistance at the maternal-fetal interface. We aimed to test the hypothesis that the Zika virus functionally disrupts placental microRNAs, enabling viral persistence and fetal pathogenesis.

STUDY DESIGN

To test this hypothesis, we used orthogonal approaches in human and murine experimental models. In primary human trophoblast cultures (n=5 donor placentae), we performed Argonaute high-throughput sequencing ultraviolet-crosslinking and immunoprecipitation to identify any significant alterations in the functional loading of microRNAs and their targets onto the RNA-induced silencing complex. Trophoblasts from same-donors were split and infected with a contemporary first-passage Zika virus strain HN16 (multiplicity of infection=1 plaque forming unit per cell) or mock infected. To functionally cross-validate microRNA-messenger RNA interactions, we compared our Argonaute high-throughput sequencing ultraviolet-crosslinking and immunoprecipitation results with an independent analysis of published bulk RNA-sequencing data from human placental disk specimens (n=3 subjects; Zika virus positive in first, second, or third trimester, CD45- cells sorted by flow cytometry) and compared it with uninfected controls (n=2 subjects). To investigate the importance of these microRNA and RNA interference networks in Zika virus pathogenesis, we used a gnotobiotic mouse model uniquely susceptible to the Zika virus. We evaluated if small-molecule enhancement of microRNA and RNA interference pathways with enoxacin influenced Zika virus pathogenesis (n=20 dams total yielding 187 fetal specimens). Lastly, placentae (n=14 total) from this mouse model were analyzed with Visium spatial transcriptomics (9743 spatial transcriptomes) to identify potential Zika virus-associated alterations in immune microenvironments.

RESULTS

We found that Zika virus infection of primary human trophoblast cells led to an unexpected disruption of placental microRNA regulation networks. When compared with uninfected controls, Zika virus-infected placentae had significantly altered SLC12A8, SDK1, and VLDLR RNA-induced silencing complex loading and transcript levels (-22; adjusted P value <.05; Wald-test with false discovery rate correction q<0.05). In silico microRNA target analyses revealed that 26 of 119 transcripts (22%) in the transforming growth factor-β signaling pathway were targeted by microRNAs that were found to be dysregulated following Zika virus infection in trophoblasts. In gnotobiotic mice, relative to mock controls, Zika virus-associated fetal pathogenesis included fetal growth restriction (P=.036) and viral persistence in placental tissue (P=.011). Moreover, spatial transcriptomics of murine placentae revealed that Zika virus-specific placental niches were defined by significant up-regulation of complement cascade components and coordinated changes in transforming growth factor-β gene expression. Finally, treatment of Zika virus-infected mice with enoxacin abolished placental Zika virus persistence, rescued the associated fetal growth restriction, and the Zika virus-associated transcriptional changes in placental immune microenvironments were no longer observed.

CONCLUSION

These results collectively suggest that (1) Zika virus infection and persistence is associated with functionally perturbed microRNA and RNA interference pathways specifically related to immune regulation in placental microenvironments and (2) enhancement of placental microRNA and RNA interference pathways in mice rescued Zika virus-associated pathogenesis, specifically persistence of viral transcripts in placental microenvironments and fetal growth restriction.

Pregnancy and SARS-CoV-2 infection with a focus on its vertical transmission, breastfeeding, cord blood banking, and vaccination during COVID-19 infection

The SARS-CoV-2 outbreak led to a health crisis worldwide. This infection can infect individuals, particularly pregnant women. In this review, we tried to find the possibility of vertical transmission of COVID-19 and investigate the effects of COVID-19 on pregnancy, breastfeeding, cord blood banking, and the effects of recommended vaccines on pregnant and lactating women. Keywords include COVID-19, congenital infection, SARS-CoV-2, pregnancy, and COVID-19 vaccines. Vertical transmission of SARS-CoV-2 was searched in scientific databases, such as PubMed, Google Scholar, and Scopus. The criteria for including studies in this article are the study of SARS-CoV-2 infection in pregnant women, fetuses, and neonates during pregnancy and while breastfeeding, and also the effect of COVID-19 vaccines on them. There are several conflicting results in the transmission of SARS-CoV-2 from the maternal-fetal interface. Since many neonates born from COVID-19-infected mothers had no signs of this infection, the possibility of SARS-CoV-2 congenital transmission cannot be confirmed. Also, SARS-CoV-2-infected women can breastfeed their babies if they have mild symptoms. Up till now, no adverse effect of COVID-19 vaccines has been identified on mothers, infants, and the fertility of men or women. Even so, more investigations are needed on the long-term effects of COVID-19 vaccines.

Association between torquetenovirus in vaginal secretions and infertility: An exploratory metagenomic analysis

PROBLEM

The association of viruses with infertility remains incompletely evaluated.

METHOD OF STUDY

Vaginal secretions from 46 women seeking treatment in the Center for Reproductive Medicine and Infertility at Weill Cornell Medicine were tested for viruses by metagenomic analysis by lab personnel blinded to all clinical data.

RESULTS

Torquetenovirus (TTV) was identified in 16 women, alphapapillomavirus in seven women and most were positive for bacteriophages. Twelve of the subjects were fertile and sought to freeze their oocytes for future implantation. These women were all negative for TTV. In contrast, 16 of the 34 women (47.1%) being treated for infertility were TTV-positive (p = .0035). Evaluating the women by cause of infertility, five of nine women (55.6%) whose male partner had inadequate sperm parameters and six of 14 women (42.9%) with defective ovulation were TTV positive (p = .0062 and p = .0171, respectively, vs. the fertile women). Alphapapillomavirus was identified in one (8.3%) fertile woman, five (35.7%) women with ovulation deficiency, and one (11.1%) woman with male factor infertility. These differences were not statistically significant. There were no differences in bacteriophage families or the presence of Lactobacillus phages between fertile or infertile women or between different causes of infertility. There was a negative association between TTV detection and Lactobacillus crispatus dominance in the vaginal microbiota (p = .0184), but no association between TTV detection and the presence of alphapapillomavirus or Candida species.

CONCLUSION

Detection of TTV in the vagina might be a biomarker for specific causes of infertility.

Viral-induced inflammation can lead to adverse pregnancy outcomes

INTRODUCTION

Parvoviruses are DNA viruses of small size. There have been a number of reports indicating the possible effects of B19 infections during pregnancy. These effects include spontaneous abortions, stillbirth, fetal damage, and quite often, fetal anemia with hydrops fetalis.

A systematic review of immune-based interventions for perinatal neuroprotection: closing the gap between animal studies and human trials

BACKGROUND

Perinatal infection/inflammation is associated with a high risk for neurological injury and neurodevelopmental impairment after birth. Despite a growing preclinical evidence base, anti-inflammatory interventions have not been established in clinical practice, partly because of the range of potential targets. We therefore systematically reviewed preclinical studies of immunomodulation to improve neurological outcomes in the perinatal brain and assessed their therapeutic potential.

METHODS

We reviewed relevant studies published from January 2012 to July 2023 using PubMed, Medline (OvidSP) and EMBASE databases. Studies were assessed for risk of bias using the SYRCLE risk of bias assessment tool (PROSPERO; registration number CRD42023395690).

RESULTS

Forty preclinical publications using 12 models of perinatal neuroinflammation were identified and divided into 59 individual studies. Twenty-seven anti-inflammatory agents in 19 categories were investigated. Forty-five (76%) of 59 studies reported neuroprotection, from all 19 categories of therapeutics. Notably, 10/10 (100%) studies investigating anti-interleukin (IL)-1 therapies reported improved outcome, whereas half of the studies using corticosteroids (5/10; 50%) reported no improvement or worse outcomes with treatment. Most studies (49/59, 83%) did not control core body temperature (a known potential confounder), and 25 of 59 studies (42%) did not report the sex of subjects. Many studies did not clearly state whether they controlled for potential study bias.

CONCLUSION

Anti-inflammatory therapies are promising candidates for treatment or even prevention of perinatal brain injury. Our analysis highlights key knowledge gaps and opportunities to improve preclinical study design that must be addressed to support clinical translation.

SARS-CoV-2 niches in human placenta revealed by spatial transcriptomics

BACKGROUND

Functional placental niches are presumed to spatially separate maternal-fetal antigens and restrict the vertical transmission of pathogens. We hypothesized a high-resolution map of placental transcription could provide direct evidence for niche microenvironments with unique functions and transcription profiles.

METHODS

We utilized Visium Spatial Transcriptomics paired with H&E staining to generate 17,927 spatial transcriptomes. By integrating these spatial transcriptomes with 273,944 placental single-cell and single-nuclei transcriptomes, we generated an atlas composed of at least 22 subpopulations in the maternal decidua, fetal chorionic villi, and chorioamniotic membranes.

FINDINGS

Comparisons of placentae from uninfected healthy controls (n = 4) with COVID-19 asymptomatic (n = 4) and symptomatic (n = 5) infected participants demonstrated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in syncytiotrophoblasts occurred in both the presence and the absence of maternal clinical disease. With spatial transcriptomics, we found that the limit of detection for SARS-CoV-2 was 1/7,000 cells, and placental niches without detectable viral transcripts were unperturbed. In contrast, niches with high SARS-CoV-2 transcript levels were associated with significant upregulation in pro-inflammatory cytokines and interferon-stimulated genes, altered metallopeptidase signaling (TIMP1), with coordinated shifts in macrophage polarization, histiocytic intervillositis, and perivillous fibrin deposition. Fetal sex differences in gene expression responses to SARS-CoV-2 were limited, with confirmed mapping limited to the maternal decidua in males.

CONCLUSIONS

High-resolution placental transcriptomics with spatial resolution revealed dynamic responses to SARS-CoV-2 in coordinate microenvironments in the absence and presence of clinically evident disease.

FUNDING

This work was supported by the NIH (R01HD091731 and T32-HD098069), NSF (2208903), the Burroughs Welcome Fund and the March of Dimes Preterm Birth Research Initiatives, and a Career Development Award from the American Society of Gene and Cell Therapy.

Impact of COVID-19 on pregnant women's health: Consequences in obstetrics two years after the pandemic

The pandemic linked to SARS-CoV-2 has profoundly disrupted the health systems and many studies have led to a better understanding of this virus, which is responsible for severe disease, particularly during pregnancy. Pregnancy is a risk factor for severe COVID-19. Term of pregnancy and vaccination status is the main risk factor in addition to classic comorbidities like general population. COVID-19 during pregnancy is responsible for more maternal death, stillbirth, pre-eclampsia spontaneous and induced prematurity. Vaccination is therefore strongly recommended for pregnant patients. In addition, the COVID-19 pandemic has highlighted a psychological and social dimension that should not be neglected in the management of a pregnant patient. Correlation between immunological changes and clinical impact are described in this review. Many conclusions can now be made and are summarized in this article in order to discuss possible future research.

Pregnancy, infection, and epigenetic regulation: A complex scenario

A unique immunological condition, pregnancy ensures fetus from maternal rejection, allows adequate fetal development, and protects against microorganisms. Infections during pregnancy may lead to devastating consequences for pregnant women and fetuses, resulting in the mother's death, miscarriage, premature childbirth, or neonate with congenital infection and severe diseases and defects. Epigenetic (heritable changes in gene expression) mechanisms like DNA methylation, chromatin modification, and gene expression modulation during gestation are linked with the number of defects in the fetus and adolescents. The feto-maternal crosstalk for fetal survival during the entire gestational stages are tightly regulated by various cellular pathways, including epigenetic mechanisms that respond to both internal as well outer environmental factors, which can influence the fetal development across the gestational stages. Due to the intense physiological, endocrinological, and immunological changes, pregnant women are more susceptible to bacterial, viral, parasitic, and fungal infections than the general population. Microbial infections with viruses (LCMV, SARS-CoV, MERS-CoV, and SARS-CoV-2) and bacteria (Clostridium perfringens, Coxiella burnetii, Listeria monocytogenes, Salmonella enteritidis) further increase the risk to maternal and fetal life and developmental outcome. If the infections remain untreated, the possibility of maternal and fetal death exists. This article focused on the severity and susceptibility to infections caused by Salmonella, Listeria, LCMV, and SARS-CoV-2 during pregnancy and their impact on maternal health and the fetus. How epigenetic regulation during pregnancy plays a vital role in deciding the fetus's developmental outcome under various conditions, including infection and other stress. A better understanding of the host-pathogen interaction, the characterization of the maternal immune system, and the epigenetic regulations during pregnancy may help protect the mother and fetus from infection-mediated outcomes.

Intrinsic sexual dimorphism in the placenta determines the differential response to benzene exposure

Maternal immune activation (MIA) by environmental challenges is linked to severe developmental complications, such as neurocognitive disorders, autism, and even fetal/maternal death. Benzene is a major toxic compound in air pollution that affects the mother as well as the fetus and has been associated with reproductive complications. Our objective was to elucidate whether benzene exposure during gestation triggers MIA and its impact on fetal development. We report that benzene exposure during pregnancy leads MIA associated with increased fetal resorptions, fetal growth, and abnormal placenta development. Furthermore, we demonstrate the existence of a sexual dimorphic response to benzene exposure in male and female placentas. The sexual dimorphic response is a consequence of inherent differences between male and female placenta. These data provide crucial information on the origins or sexual dimorphism and how exposure to environmental factors can have a differential impact on the development of male and female offspring.

SARS-CoV-2 Footprints in the Placenta: What We Know after Three Years of the Pandemic

As the COVID-19 pandemic continues into its third year, there is accumulating evidence on the consequences of maternal infection. Emerging data indicate increased obstetrics risks, including maternal complications, preterm births, impaired intrauterine fetal growth, hypertensive disorders, stillbirth, gestational diabetes, and a risk of developmental defects in neonates. Overall, controversial concerns still exist regarding the potential for vertical transmission. Histopathological examination of the placenta can represent a useful instrument for investigation and can contribute significant information regarding the possible immunohistopathological mechanisms involved in developing unfavorable perinatal outcomes. Based on current evidence, SARS-CoV-2 infection can affect placental tissue by inducing several specific changes. The level of placental involvement is considered one of the determining factors for unfavorable outcomes during pregnancy due to inflammation and vascular injuries contributing to complex cascade immunological and biological events; however, available evidence does not indicate a strong and absolute correlation between maternal infection, placental lesions, and obstetric outcomes. As existing studies are still limited, we further explore the placenta at three different levels, using histology, immunohistochemistry, and molecular genetics to understand the epidemiological and virological changes observed in the ongoing pandemic.

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.

Effect of severe acute respiratory syndrome coronavirus 2 infection during pregnancy in K18-hACE2 transgenic mice

OBJECTIVE

This study aimed to examine the influence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on pregnancy in cytokeratin-18 (K18)-hACE2 transgenic mice.

METHODS

To determine the expression of hACE2 mRNA in the female reproductive tract of K18-hACE2 mice, real-time polymerase chain reaction (RT-PCR) was performed using the ovary, oviduct, uterus, umbilical cord, and placenta. SARS-CoV-2 was inoculated intranasally (30 μL/mouse, 1×104 TCID50/mL) to plug-checked K18-hACE2 homozygous female mice at the pre-and post-implantation stages at 2.5 days post-coitum (dpc) and 15.5 dpc, respectively. The number of implantation sites was checked at 7.5 dpc, and the number of normally born pups was investigated at 20.5 dpc. Pregnancy outcomes, including implantation and childbirth, were confirmed by comparison with the non-infected group. Tissues of infected mice were collected at 7.5 dpc and 19.5 dpc to confirm the SARS-CoV-2 infection. The infection was identified by performing RT-PCR on the infected tissues and comparing them to the non-infected tissues.

RESULTS

hACE2 mRNA expression was confirmed in the female reproductive tract of the K18-hACE2 mice. Compared to the non-infected group, no significant difference in the number of implantation sites or normally born pups was found in the infected group. SARS-CoV-2 infection was detected in the lungs but not in the female reproductive system of infected K18-hACE2 mice.

CONCLUSION

In K18-hACE2 mice, intranasal infection with SARS-CoV-2 did not induce implantation failure, preterm labor, or miscarriage. Although the viral infection was not detected in the uterus, placenta, or fetus, the infection of the lungs could induce problems in the reproductive system. However, lung infections were not related to pregnancy outcomes.

Understanding the Immune System in Fetal Protection and Maternal Infections during Pregnancy

The fetal-maternal immune system determines the fate of pregnancy. The trophoblast cells not only give an active response against external stimuli but are also involved in secreting most of the cytokines. These cells have an essential function in fetal acceptance or fetal rejection. Other immune cells also play a pivotal role in carrying out a successful pregnancy. The disruption in this mechanism may lead to harmful effects on pregnancy. The placenta serves as an immune barrier in fetus protection against invading pathogens. Once the infections prevail, they may localize in placental and fetal tissues, and the presence of inflammation due to cytokines may have detrimental effects on pregnancy. Moreover, some pathogens are responsible for congenital fetal anomalies and affect almost all organs of the developing fetus. This review article is designed to address the bacterial and viral infections that threaten pregnancy and their possible outcomes. Moreover, training of the fetal immune system against the exposure of infections and the role of CD49a + NK cells in embryonic development will also be highlighted.

Gradient Boosting Machine Learning Model for Defective Endometrial Receptivity Prediction by Macrophage-Endometrium Interaction Modules

Background

A receptive endometrium is a prerequisite for successful embryo implantation. Mounting evidence shows that nearly one-third of infertility and implantation failures are caused by defective endometrial receptivity. This study pooled 218 subjects from multiple datasets to investigate the association of the immune infiltration level with reproductive outcome. Additionally, macrophage-endometrium interaction modules were constructed to explore an accurate and cost-effective approach to endometrial receptivity assessment.

Methods

Immune-infiltration levels in 4 GEO datasets (n=218) were analyzed and validated through meta-analysis. Macrophage-endometrium interaction modules were selected based on the weighted gene co-expression network in GSE58144 and differentially expressed genes dominated by GSE19834 dataset. Xgboost, random forests, and regression algorithms were applied to predictive models. Subsequently, the efficacy of the models was compared and validated in the GSE165004 dataset. Forty clinical samples (RT-PCR and western blot) were performed for expression and model validation, and the results were compared to those of endometrial thickness in clinical pregnancy assessment.

Results

Altered levels of Mϕs infiltration were shown to critically influence embryo implantation. The three selected modules, manifested as macrophage-endometrium interactions, were enrichment in the immunoreactivity, decidualization, and signaling functions and pathways. Moreover, hub genes within the modules exerted significant reproductive prognostic effects. The xgboost algorithm showed the best performance among the machine learning models, with AUCs of 0.998 (95% CI 0.994-1) and 0.993 (95% CI 0.979-1) in GSE58144 and GSE165004 datasets, respectively. These results were significantly superior to those of the other two models (random forest and regression). Similarly, the model was significantly superior to ultrasonography (endometrial thickness) with a better cost-benefit ratio in the population.

Conclusion

Successful embryo implantation is associated with infiltration levels of Mϕs, manifested in genetic modules involved in macrophage-endometrium interactions. Therefore, utilizing the hub genes in these modules can provide a platform for establishing excellent machine learning models to predict reproductive outcomes in patients with defective endometrial receptivity.

IL-22 Plays a Dual Role in the Amniotic Cavity: Tissue Injury and Host Defense against Microbes in Preterm Labor

IL-22 is a multifaceted cytokine with both pro- and anti-inflammatory functions that is implicated in multiple pathologies. However, the role of IL-22 in maternal-fetal immunity in late gestation is poorly understood. In this study, we first showed that IL-22+ T cells coexpressing retinoic acid-related orphan receptor γt (ROR-γt) are enriched at the human maternal-fetal interface of women with preterm labor and birth, which was confirmed by in silico analysis of single-cell RNA sequencing data. T cell activation leading to preterm birth in mice was preceded by a surge in IL-22 in the maternal circulation and amniotic cavity; however, systemic administration of IL-22 in mice did not induce adverse perinatal outcomes. Next, using an ex vivo human system, we showed that IL-22 can cross from the choriodecidua to the intra-amniotic space, where its receptors (Il22ra1, Il10rb, and Il22ra2) are highly expressed by murine gestational and fetal tissues in late pregnancy. Importantly, amniotic fluid concentrations of IL-22 were elevated in women with sterile or microbial intra-amniotic inflammation, suggesting a dual role for this cytokine. The intra-amniotic administration of IL-22 alone shortened gestation and caused neonatal death in mice, with the latter outcome involving lung maturation and inflammation. IL-22 plays a role in host response by participating in the intra-amniotic inflammatory milieu preceding Ureaplasma parvum-induced preterm birth in mice, which was rescued by the deficiency of IL-22. Collectively, these data show that IL-22 alone is capable of causing fetal injury leading to neonatal death and can participate in host defense against microbial invasion of the amniotic cavity leading to preterm labor and birth.

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.

Vertical Transmission and Neonatal Outcomes Following Maternal SARS-CoV-2 Infection During Pregnancy

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 200 million people worldwide and has likely exposed millions of neonates to SARS-CoV-2 in utero. A large body of literature has examined the possibility of vertical transmission from pregnant women infected with SARS-CoV-2 to their neonates. In this chapter, we review mechanisms of-and evidence for-vertical transmission of SARS-CoV-2, including transplacental, through other biospecimens and breastfeeding, and discuss neonatal outcomes following in utero exposure. Based on the available literature, we conclude vertical transmission of SARS-CoV-2 is rare, and exposed neonates generally show favorable health outcomes.

Leucine supplementation during late gestation globally alters placental metabolism and nutrient transport via modulation of the PI3K/AKT/mTOR signaling pathway in sows

In a previously published study we reported that sow dietary leucine supplementation during late pregnancy significantly improved newborn piglet birth weight by stimulating protein synthesis in the longissimus dorsi muscle. However, there is still limited knowledge as to whether leucine can exert its effects on the placenta, one of the most important temporal organs during pregnancy, to promote maternal-fetal nutrient supply and thus contribute to fetal intrauterine development. Therefore, we tested this hypothesis in the present study. In total, 150 sows at day 90 of gestation were divided into three groups and fed with either a control diet (CON), CON + 0.4% Leu or CON + 0.8% Leu, respectively, until parturition. Placental metabolomics, full spectrum amino acids and nutrient transporters were systematically analyzed after sample collection. The results indicated that Leu supplementation led to an altered placental metabolism with an increased number of metabolites related to glycolysis and the oxidation of fatty acids, as well as elevated levels of amino acid accumulation in the placenta. In addition, nutrient transporters of amino acids, glucose and fatty acids in the placenta were globally up-regulated and several enzymes related to energy metabolism, including hexokinase, succinate dehydrogenase, lactated hydrogenase, glycogen phosphorylase and hydroxyacyl-CoA-dehydrogenase, were also significantly increased with no change observed in the antioxidative status of those groups with Leu supplementation. Furthermore, the phosphorylation of PI3K, Akt, and mTOR was enhanced in the placenta of sows undergoing Leu treatment. Collectively, we concluded that supplementing the diets of sows with Leu during late gestation globally altered placental metabolism and promoted maternal-fetus nutrient transport (amino acids, glucose, and fatty acids) via modulation of the PI3K/Akt/mTOR signaling pathway.

The female reproductive tract virome: understanding the dynamic role of viruses in gynecological health and disease

The human body is inhabited by a large and complex network of commensal and predatory eukaryotic viruses and bacteriophages collectively termed the virome. Despite being the most abundant and genetically diverse biological entities on the planet, the impact of viruses on human health especially within the female reproductive tract (FRT) remains understudied. To better appreciate current knowledge regarding the dynamic role of viruses in FRT health and disease, in this review we highlight the known constituents of the FRT virome, transkingdom interactions within the FRT and their influence on gynecological disease. A better understanding of the FRT virome may pave the way toward improved outcomes in gynecological, reproductive, and neonatal health.

The Effect of HSV-1 Seropositivity on the Course of Pregnancy, Childbirth and the Condition of Newborns

The goal of this research was to evaluate seropositivity to HSV-1 among pregnant women and its effect on the course of pregnancy, childbirth and the condition of newborns. Methods: The serological status, socio-demographic characteristics, parity of pregnancy and childbirth and condition of newborns in women seronegative and seropositive to HSV-1 with recurrent infection and its latent course during pregnancy were analyzed. Newborns from these mothers made up the corresponding groups. Results: Low titers of IgG antibodies to HSV-1 in women in the first trimester of pregnancy are associated with threatened miscarriage, anemia in pregnancy and chronic placental insufficiency. High titers of IgG antibodies to HSV-1 in women in the second trimester of pregnancy are associated with late miscarriages and premature births, anemia in pregnancy, chronic placental insufficiency, labor anomalies, early neonatal complications (cerebral ischemia, respiratory distress syndrome) and localized skin rashes. Low titers of IgG antibodies to HSV-1 in women in the third trimester of pregnancy are associated with premature birth, anemia in pregnancy, chronic placental insufficiency, endometritis, complications of the early neonatal period and localized skin rashes. Conclusions: Our research showed that low or high titers of IgG antibodies to HSV-1, determined by the timing of recurrence of infection during pregnancy, are associated with a high incidence of somatic pathology and complications in pregnancy, childbirth and the neonatal period.

SARS-CoV-2 infection during pregnancy and risk of preeclampsia: a systematic review and meta-analysis

OBJECTIVE

To examine the relationship between SARS-CoV-2 infection during pregnancy and the risk for preeclampsia.

DATA SOURCES

MEDLINE, Embase, POPLINE, CINAHL, LILACS, and the World Health Organization COVID-19, Chinese, and preprint databases (all from December 1, 2019, to May 31, 2021). Google Scholar, bibliographies, and conference proceedings were also searched.

STUDY ELIGIBILITY CRITERIA

Observational studies that assessed the association between SARS-CoV-2 infection during pregnancy and preeclampsia and that reported unadjusted and/or adjusted risk estimates and 95% confidence intervals or data to calculate them.

STUDY APPRAISAL AND SYNTHESIS METHODS

The primary outcome was preeclampsia. Secondary outcomes included preeclampsia with severe features, preeclampsia without severe features, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. Two reviewers independently reviewed studies for inclusion, assessed their risk of bias, and extracted data. Pooled unadjusted and adjusted odds ratios with 95% confidence intervals, and 95% prediction interval were calculated. Heterogeneity was quantified using the І2 statistic, for which І2≥30% indicated substantial heterogeneity. Subgroup and sensitivity analyses were performed to test the robustness of the overall findings.

RESULTS

A total of 28 studies comprising 790,954 pregnant women, among which 15,524 were diagnosed with SARS-CoV-2 infection, met the inclusion criteria. The meta-analysis of unadjusted odds ratios showed that the odds of developing preeclampsia were significantly higher among pregnant women with SARS-CoV-2 infection than among those without SARS-CoV-2 infection (7.0% vs 4.8%; pooled odds ratio, 1.62; 95% confidence interval, 1.45-1.82; P<.00001; І2=17%; 26 studies; 95% prediction interval of the odds ratio, 1.28-2.05). The meta-analysis of adjusted odds ratios also showed that SARS-CoV-2 infection during pregnancy was associated with a significant increase in the odds of preeclampsia (pooled odds ratio, 1.58; 95% confidence interval, 1.39-1.80; P<.0001; І2=0%; 11 studies). There was a statistically significant increase in the odds of preeclampsia with severe features (odds ratio, 1.76; 95% confidence interval, 1.18-2.63; І2=58%; 7 studies), eclampsia (odds ratio, 1.97; 95% confidence interval, 1.01-3.84; І2=0%, 3 studies), and HELLP syndrome (odds ratio, 2.10; 95% confidence interval, 1.48-2.97; 1 study) among pregnant women with SARS-CoV-2 infection when compared to those without the infection. Overall, the direction and magnitude of the effect of SARS-CoV-2 infection during pregnancy on preeclampsia was consistent across most prespecified subgroup and sensitivity analyses. Both asymptomatic and symptomatic SARS-CoV-2 infections significantly increased the odds of developing preeclampsial; however, it was higher among patients with symptomatic illness (odds ratio, 2.11; 95% confidence interval, 1.59-2.81) than among those with asymptomatic illness (odds ratio, 1.59; 95% confidence interval, 1.21-2.10).

CONCLUSION

SARS-CoV-2 during pregnancy is associated with higher odds of preeclampsia.

HIV, Placental Lesions, and Adverse Perinatal Outcomes

Africa has the highest number of pregnant women with human immunodeficiency virus (HIV). In some studies, HIV has been associated with adverse perinatal outcomes. However, the pathophysiological mechanism leading to adverse fetal outcomes is not known. Maternal vascular malformation, chorioamnionitis, and decreased placental weight have been described as placental features associated with HIV in some studies. The use of antiretroviral therapy has reduced perinatal transmission of HIV and adverse fetal outcomes. However, placental mechanisms associated with HIV and the fetal immune response to maternal HIV infection are poorly understood. Additional research is required to understand whether altered maternal immunity in women living with HIV can trigger fetal responses leading to stillbirth or preterm birth.

Placenta in the Critically Ill Mother

The placenta is a temporary, multifunctional organ composed of both maternal and fetal components. It maintains homeostasis to ensure the growth of the fetus and well-being of the mother. Abnormalities in placental development have been known to be responsible for several disorders of pregnancy. Conditions coincident with pregnancy can upset the homeostasis and result in critical illness, which can greatly impact placental function and in turn affect the fetus. Decreased blood flow, acidemia, hypercarbia, and hypoxia seen in critically ill pregnant mothers can result in fetal death. Understanding the physiological changes and functioning of the maternal-fetal-placental unit will aid in better management of critically ill mothers.

How to cite this article

Taggarsi DA, Krishna B. Placenta in the Critically Ill Mother. Indian J Crit Care Med 2021;25(Suppl 3):S200-S205.

Pregnancy and pandemics: Interaction of viral surface proteins and placenta cells

Throughout history, pandemics of infectious diseases caused by emerging viruses have spread worldwide. Evidence from previous outbreaks demonstrated that pregnant women are at high risk of contracting the diseases and suffering from adverse outcomes. However, while some viruses can cause major health complications for the mother and her fetus, others do not appear to affect pregnancy. Viral surface proteins bind to specific receptors on the cellular membrane of host cells and begin therewith the infection process. During pregnancy, the molecular features of these proteins may determine specific target cells in the placenta, which may explain the different outcomes. In this review, we display information on Variola, Influenza, Zika and Corona viruses focused on their surface proteins, effects on pregnancy, and possible target placental cells. This will contribute to understanding viral entry during pregnancy, as well as to develop strategies to decrease the incidence of obstetrical problems in current and future infections.

COVID-19 in pregnancy: placental pathological patterns and effect on perinatal outcome in five cases

INTRODUCTION

COVID-19, the disease caused by the novel coronavirus SARS-CoV-2, is a severe systemic thrombotic syndrome that emerged in 2019, with an ensuing pandemic. To evaluate the impact of this disease on placental tissue and perinatal outcome, histological, immunohistochemical and ultrastructural analyses of placental tissue were performed for five cases of pregnant women with COVID-19.

CASE REPORTS

All five pregnant women in this series developed COVID-19 in late pregnancy. Two patients experienced respiratory distress, and computed tomography revealed signs of pneumonia, with bilateral involvement, multiple lobular and subsegmental areas of consolidation and ground-glass opacities. Histological studies of placental tissue revealed the presence of slight signs of maternal vascular underperfusion (MVUs) or foetal vascular underperfusion (FVUs) lesions and mild inflammatory lesions. CD15 immunoreactivity in the placental tissue was low in all cases, demonstrating that in these cases there was not severe foetal hypoxia/asphyxia risk for newborns or distal vascular immaturity. In all cases examined, ultrastructural analyses showed spherical-like coronavirus particles with an electron intermediate-density core as well as projections from the surface as spike-like structures in the syncytiotrophoblasts. At term, all of the women delivered newborns who were negative for SARS-CoV-2 by nasopharyngeal testing in their first day of life. All newborns were exclusively breastfed and were discharged on the 3rd day of life.

CONCLUSIONS

In conclusion, placental patterns in pregnancy due to COVID-19 in the late stage of gestation indicate no evidence of vertical trans-placental SARS-CoV-2 transmission or a significant impact on the perinatal outcome of newborns, in both mild and more severe cases.

Natural versus Laboratory World: Incorporating Wild-Derived Microbiota into Preclinical Rodent Models

Advances in data collection (high-throughput shotgun metagenomics, transcriptomics, and metabolomics) and analysis (bioinformatics and multiomics) led to the realization that all mammals are metaorganisms, shaped not only by their own genome but also by the genomes of the microbes that colonize them. To date, most studies have focused on the bacterial microbiome, whereas curated databases for viruses, fungi, and protozoa are still evolving. Studies on the interdependency of microbial kingdoms and their combined effects on host physiology are just starting. Although it is clear that past and present exposure to commensals and pathogens profoundly affect human physiology, such exposure is lacking in standard preclinical models such as laboratory mice. Laboratory mouse colonies are repeatedly rederived in germ-free status and subjected to restrictive, pathogen-free housing conditions. This review summarizes efforts to bring the wild microbiome into the laboratory setting to improve preclinical models and their translational research value.

Inflammasome signaling in human placental trophoblasts regulates immune defense against Listeria monocytogenes infection

The human placenta is a dynamic organ that modulates physiological adaptations to pregnancy. To define the immunological signature of the human placenta, we performed unbiased profiling of secreted immune factors from human chorionic villi isolated from placentas at mid and late stages of pregnancy. We show that placental trophoblasts constitutively secrete the inflammasome-associated cytokines IL-1β and IL-18, which is blocked by NLRP3 inflammasome inhibitors and occurs without detectable gasdermin D cleavage. We further show that placenta-derived IL-1β primes monocytes for inflammasome induction to protect against Listeria monocytogenes infection. Last, we show that the human placenta responds to L. monocytogenes infection through additional inflammasome activation and that inhibition of this pathway sensitizes villi to infection. Our results thus identify the inflammasome as an important mechanism by which the human placenta regulates systemic and local immunity during pregnancy to defend against L. monocytogenes infection.

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

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

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

Role of ACE2 in pregnancy and potential implications for COVID-19 susceptibility

In times of coronavirus disease 2019 (COVID-19), the impact of severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 infection on pregnancy is still unclear. The presence of angiotensin-converting enzyme (ACE) 2 (ACE2), the main receptor for SARS-CoV-2, in human placentas indicates that this organ can be vulnerable for viral infection during pregnancy. However, for this to happen, additional molecular processes are critical to allow viral entry in cells, its replication and disease manifestation, particularly in the placenta and/or feto-maternal circulation. Beyond the risk of vertical transmission, COVID-19 is also proposed to deplete ACE2 protein and its biological actions in the placenta. It is postulated that such effects may impair essential processes during placentation and maternal hemodynamic adaptations in COVID-19 pregnancy, features also observed in several disorders of pregnancy. This review gathers information indicating risks and protective features related to ACE2 changes in COVID-19 pregnancies. First, we describe the mechanisms of SARS-CoV-2 infection having ACE2 as a main entry door and current evidence of viral infection in the placenta. Further, we discuss the central role of ACE2 in physiological systems such as the renin-angiotensin system (RAS) and the kallikrein-kinin system (KKS), both active during placentation and hemodynamic adaptations of pregnancy. Significant knowledge gaps are also identified and should be urgently filled to better understand the fate of ACE2 in COVID-19 pregnancies and the potential associated risks. Emerging knowledge will be able to improve the early stratification of high-risk pregnancies with COVID-19 exposure as well as to guide better management and follow-up of these mothers and their children.

Maternal respiratory SARS-CoV-2 infection in pregnancy is associated with a robust inflammatory response at the maternal-fetal interface

BACKGROUND

Pregnant women are at increased risk for severe outcomes from coronavirus disease 2019 (COVID-19), but the pathophysiology underlying this increased morbidity and its potential effect on the developing fetus is not well understood.

METHODS

We assessed placental histology, ACE2 expression, and viral and immune dynamics at the term placenta in pregnant women with and without respiratory severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

FINDINGS

The majority (13 of 15) of placentas analyzed had no detectable viral RNA. ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term, suggesting that low ACE2 expression may protect the term placenta from viral infection. Using immortalized cell lines and primary isolated placental cells, we found that cytotrophoblasts, the trophoblast stem cells and precursors to syncytiotrophoblasts, rather than syncytiotrophoblasts or Hofbauer cells, are most vulnerable to SARS-CoV-2 infection in vitro. To better understand potential immune mechanisms shielding placental cells from infection in vivo, we performed bulk and single-cell transcriptomics analyses and found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited robust immune responses, including increased activation of natural killer (NK) and T cells, increased expression of interferon-related genes, as well as markers associated with pregnancy complications such as preeclampsia.

CONCLUSIONS

SARS-CoV-2 infection in late pregnancy is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion.

FUNDING

NIH (T32GM007205, F30HD093350, K23MH118999, R01AI157488, U01DA040588) and Fast Grant funding support from Emergent Ventures at the Mercatus Center.

Hematological Profile of Pregnant Women with Suspected Zika Virus Infection Followed Up at a Referral Service in Manaus, Brazil

The purpose of this paper is to describe the hematological profile of pregnant women with suspected Zika virus (ZIKV) infection followed up at a reference service for infectious diseases in Manaus, Brazil, through a clinical, epidemiological, cross-sectional study of pregnant women with an exanthematic manifestation who looked for care between 2015 and 2017. The participants were 499 pregnant women, classified into four subgroups, according to laboratory confirmation of infections: ZIKV-positive; ZIKV-positive and positive for another infection; positive for another infection but not ZIKV-positive; and not positive for any of the infections investigated. Hematological parameters were analyzed descriptively. The association between maternal infection and the hematological profile, along with the association between the maternal hematological profile and the gestational outcome, were tested. Similar hematic and platelet parameters were observed among pregnant women. However, a significant association was observed between low maternal lymphocyte count and a positive diagnosis for ZIKV (p < 0.001). The increase in maternal platelet count and the occurrence of unfavorable gestational outcome were positively associated. A similar hematic and platelet profile was identified among pregnant women, differing only in the low lymphocyte count among ZIKV-positive pregnant women. Regarding gestational outcomes, in addition to the damage caused by ZIKV infection, altered maternal platelets may lead to unfavorable outcomes, with the need for adequate follow-up during prenatal care.

COVID-19 during pregnancy should we really worry from vertical transmission or rather from fetal hypoxia and placental insufficiency? A systematic review

Background

COVID-19 is the largest outbreak to strike humanity. The wide scale of fatalities and morbidities lead to a concurrent pandemic of uncertainty in scientific evidence. Conflicting evidences are released on daily basis about the neonatal outcomes of COVID-19-positive mothers. The aim of this study was to use the relevant case reports and series to determine the percentage of newborns who test positive for COVID-19 who are born to COVID-19-positive mothers. Secondary outcomes included examining laboratory abnormalities among COVID-19-positive neonates, and any depicted placental abnormalities in COVID-19-positive mothers. For this purpose, systematic review was performed on all studies reporting primary data on fetus-mother pairs with COVID-19. Data bases were searched for studies that met our inclusion and exclusion criteria.

Results

Final screening revealed 67 studies, from which the primary data of 1787 COVID-19 mothers were identified and had their pregnancy outcome analyzed. Only 2.8% of infants born to COVID-19-positive mothers tested positive, and this finding is identical to percentages reported in former Coronaviridae outbreaks, whereas 20% manifested with intrauterine hypoxia alongside placental abnormalities suggestive of heavy placental vaso-occlusive involvement.

Conclusions

These findings suggest that while vertical transmission is unlikely, there appears to be an underlying risk of placental insufficiency due to the prothrombotic tendency observed in COVID-19 infection. Guidelines for proper prophylactic anticoagulation in COVID-positive mothers need to be established.

COVID-19 and developmental origins of health and disease

From the moment of the identification of SARS-CoV-2 as an etiological agent of the severe clinical pictures of pneumonia that were being slowly observed all over the world, numerous studies have been conducted to increase the knowledge about what was an unknown virus until then. The efforts were mainly aimed to acquire epidemiological, microbiological, pathogenetic, clinical, diagnostic, therapeutic and preventive information in order to increase the available weapons to fight an infection which was rapidly taking on the characteristics of the pandemic. Given the topicality of the problem, not everything has yet been fully understood and clarified, especially in the maternal-fetal‑neonatal field, where we are beginning to question what could be the outcomes of newborn babies born to mothers who contracted SARS-CoV-2 infection during pregnancy. Thus, the aim of this review is to analyze the long-term outcomes of this infection that could affect the offspring, regardless of a possible maternal-fetal transmission, focusing on, above all, the role of maternal immune activation and the expression of the Angiotensin-converting enzyme 2 (ACE2) in particular at the placental level.

Vertical transmission of Zika virus and its outcomes: a Bayesian synthesis of prospective studies

BACKGROUND

Prospective studies of Zika virus in pregnancy have reported rates of congenital Zika syndrome and other adverse outcomes by trimester. However, Zika virus can infect and damage the fetus early in utero, but clear before delivery. The true vertical transmission rate is therefore unknown. We aimed to provide the first estimates of underlying vertical transmission rates and adverse outcomes due to congenital infection with Zika virus by trimester of exposure.

METHODS

This was a Bayesian latent class analysis of data from seven prospective studies of Zika virus in pregnancy. We estimated vertical transmission rates, rates of Zika-virus-related and non-Zika-virus-related adverse outcomes, and the diagnostic sensitivity of markers of congenital infection. We allowed for variation between studies in these parameters and used information from women in comparison groups with no PCR-confirmed infection, where available.

FINDINGS

The estimated mean risk of vertical transmission was 47% (95% credible interval 26 to 76) following maternal infection in the first trimester, 28% (15 to 46) in the second, and 25% (13 to 47) in the third. 9% (4 to 17) of deliveries following infections in the first trimester had symptoms consistent with congenital Zika syndrome, 3% (1 to 7) in the second, and 1% (0 to 3) in the third. We estimated that in infections during the first, second, and third trimester, respectively, 13% (2 to 27), 3% (-5 to 14), and 0% (-7 to 11) of pregnancies had adverse outcomes attributable to Zika virus infection. Diagnostic sensitivity of markers of congenital infection was lowest in the first trimester (42% [18 to 72]), but increased to 85% (51 to 99) in trimester two, and 80% (42 to 99) in trimester three. There was substantial between-study variation in the risks of vertical transmission and congenital Zika syndrome.

INTERPRETATION

This preliminary analysis recovers the causal effects of Zika virus from disparate study designs. Higher transmission in the first trimester is unusual with congenital infections but accords with laboratory evidence of decreasing susceptibility of placental cells to infection during pregnancy.

FUNDING

European Union Horizon 2020 programme.

Severe SARS-CoV-2 placenta infection can impact neonatal outcome in the absence of vertical transmission

The effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the pathophysiology of the placenta and its impact on pregnancy outcome has not yet been fully elucidated. Here, we present a comprehensive clinical, morphological, and molecular analysis of placental tissues from pregnant women with and without SARS-CoV-2 infection. SARS-CoV-2 could be detected in half of placental tissues from SARS-CoV-2-positive women. The presence of the virus was not associated with any distinctive pathological, maternal, or neonatal outcome features. SARS-CoV-2 tissue load was low in all but one patient who exhibited severe placental damage leading to neonatal neurological manifestations. The placental transcriptional response induced by high viral load of SARS-CoV-2 showed an immunopathology phenotype similar to autopsy lung tissues from patients with severe coronavirus disease 2019. This finding contrasted with the lack of inflammatory response in placental tissues from SARS-CoV-2-positive women with low viral tissue load and from SARS-CoV-2-negative women. Importantly, no evidence of vertical transmission of SARS-CoV-2 was found in any newborns, suggesting that the placenta may be an effective maternal-neonatal barrier against the virus even in the presence of severe infection. Our observations suggest that severe placental damage induced by the virus may be detrimental for the neonate independently of vertical transmission.

COVID-19 during pregnancy and adverse outcomes: Concerns and recommendations from The Brazilian Teratology Information Service

SARS-CoV-2 virus was first identified in the beginning of 2020 and has spread all over the world, causing the Coronavirus Disease 2019 (COVID-19) pandemic. The virus is a member of the Coronavirus family, which includes viruses that cause common cold, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). MERS and SARS are known by causing adverse events in pregnancy. Considering that SARS-CoV-2 is a new infection agent, little is known about the risk of its infection to human embryo/fetal development. However, SARS and MERS were associated with negative outcomes, such as miscarriage, preterm birth, intrauterine growth restriction and perinatal death. Here, we raise concerns and possibilities related the harmful potential of SARS-CoV-2 and COVID-19 to pregnancy, discussing symptoms, immunological changes during pregnancy, SARS-CoV-2 mutation rate (and the risks related to it). Finally, we point out recommendations to be performed by the scientific community and health care workers in order to identify and to manage potential risks to pregnant women and their babies.

Generation COVID-19 - Should the foetus be worried?

Aim

The aim of this narrative review was to evaluate the risks, both direct and indirect, to the foetus from the COVID‐19 pandemic.

Methods

Direct and indirect risks were defined as (a) vertical infection (congenital or intrapartum), (b) maternal infection and its sequelae, and (c) sources of maternal stress during lockdown, including social isolation and altered healthcare provision.

Results

Early studies suggest that vertical viral transmission is low; however, there may be an important effect of maternal infection on foetal growth and development. The impact of various degrees of lockdown on prospective mothers’ health, habits and healthcare provision is of concern. In particular, increased maternal stress has been shown to have a significant effect on foetal brain development increasing the risk of mental health, and cognitive and behavioural disorders in later life.

Conclusion

From the evidence available to date, direct risks to the foetus from the SARS‐CoV‐2 virus are low. Indirect effects of the pandemic, particularly resulting from the effect of maternal stress on the developing brain, can have lifelong detrimental impacts for this generation of children.

SARS-CoV-2 infection in pregnancy is associated with robust inflammatory response at the maternal-fetal interface

Pregnant women appear to be at increased risk for severe outcomes associated with COVID-19, but the pathophysiology underlying this increased morbidity and its potential impact on the developing fetus is not well understood. In this study of pregnant women with and without COVID-19, we assessed viral and immune dynamics at the placenta during maternal SARS-CoV-2 infection. Amongst uninfected women, ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term. Term placentas from women infected with SARS-CoV-2, however, displayed a significant increase in ACE2 levels. Using immortalized cell lines and primary isolated placental cells, we determined the vulnerability of various placental cell types to direct infection by SARS-CoV-2 in vitro. Yet, despite the susceptibility of placental cells to SARS-CoV-2 infection, viral RNA was detected in the placentas of only a subset (~13%) of women in this cohort. Through single cell transcriptomic analyses, we found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited markers associated with pregnancy complications, such as preeclampsia, and robust immune responses, including increased activation of placental NK and T cells and increased expression of interferon-related genes. Overall, this study suggests that SARS-CoV-2 is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion. While this likely represents a protective mechanism shielding the placenta from infection, inflammatory changes in the placenta may also contribute to poor pregnancy outcomes and thus warrant further investigation.

Placental pathology of the third trimester pregnant women from COVID-19

Aims

To explore the clinical characteristics and placental pathological changes of pregnant women with 2019 novel coronavirus (CoV) disease (COVID-19) in the third trimester, and to assess the possibility of vertical transmission.

Methods and results

The placenta tissues were evaluated by using immunohistochemistry for inflammatory cells and Hofbauer cells, and using severe acute respiratory syndrome (SARS) CoV-2 RNA Fluorescence In-Situ Hybridization (FISH) and SARS-CoV-2 spike protein immunofluorescence (IF) double staining. All eight placentas from the third trimester pregnancy women were studied. All patients were cured, no clinical or serological evidence pointed to vertical transmission of SARS-CoV-2. Features of maternal vascular malperfusion (MVM) such as increased syncytial knots were present in all 8 cases (8/8), and increased focal perivillous fibrin depositions were presented in 7 cases (7/8). No significate chronic histiocytic intervillositis was noted in the placenta. The number of macrophages and inflammatory cells such as T cells, B cells and plasma cells in the placental villous was not significantly increased in all cases. Moreover, all of eight cases demonstrated negative results by FISH using a SARS-CoV-2 virus RNA probe and by IF using a monoclonal antibody against SARS-CoV-2 spike protein.

Conclusions

We found no evidence of vertical transmission and adverse maternal-fetal outcomes in the placentas of third trimester COVID-19 pregnancy women, which provided further information for the clinical management of those women in the third trimester. However, further studies are still needed for patients with infections in different stage of gestation, especially in first and second trimester.

Impact of SARS-CoV-2 Infection During Pregnancy on Infant Neurobehavioral Development: A Case-Control Study

Background: Previous studies on the pneumonia outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have focused on the general population and pregnant women, while little is known about the effects of SARS-CoV-2 on retardation during and after pregnancy. The purpose of this study was to evaluate the potential influence of SARS-CoV-2 on infant neurobehavioral development. Methods: A case-control study was conducted in Wuhan Maternal and Child Health Hospital, China. Nine pregnant women with SARS-CoV-2 infection and 9 controls matched by maternal age, parity, and status of chronic disease were included. Infantile neurobehavioral development was assessed through the Ages and Stages Questionnaires Edition 3 (ASQ-3). Results: The majority of pregnant women with SARS-CoV-2 experienced cesarean section (7 of 9), which was higher than the control group (5 of 9). The throat swabs of all newborn were negative. We found that compared with the control group, neonates of mothers with SARS-CoV-2 infection during pregnancy had lower scores in communication, gross movement, fine movement, problem solving, and personal-social domains; but only fine movement domain yielded statistical significance (P = 0.031). Conclusion: Infection with SARS-CoV-2 during pregnancy may have a certain impact on infant neurobehavioral development. Further studies with larger sample size are warranted for validation.