Folate Receptor Beta Signaling in the Regulation of Macrophage Antimicrobial Immune Response: A Scoping Review

Introduction

Folate, vitamin B9, is a water-soluble vitamin that is essential to cellular proliferation and division. In addition to the reduced folate carrier, eukaryotic cells take up folate through endocytosis mediated by one of two GPI-anchored folate receptors (FRs), FRα or FRβ. Two other isoforms of FR exist, FRγ and FRδ, neither of which support endocytic activities of FR signaling. FRβ is expressed primarily by monocytes and macrophages and highly expressed on activated macrophages. Macrophage expression of FRβ suggests a role for this receptor in modulating function of these immune sentinels, particularly as they engage in inflammatory processes. Despite several studies suggesting that folates can suppress inflammatory responses of macrophages to proinflammatory stimuli, there appears to be a lack of basic research examining the role of FRβ in modulating macrophage responses to microbial sensing. We therefore conducted a scoping review to assess evidence within the published literature addressing the question, "what is known about the extent to which FRβ regulates macrophage responses to sensing, and responding to, microorganisms?".

Methods

As a strategy for the study selection, we queried articles indexed in the research database PubMed and the search engine Google Scholar (up until August 12, 2023), including combinations of the research words: macrophage, folate receptor beta, FOLR2.

Results

We identified 2 relevant articles out of 153 that are worth discussing here, none of which directly addressed our research question.

Conclusion

There is an unmet need to better define the contribution of FRβ to regulating the macrophage response to microbes.

Impact of Metabolic Stress on BeWo Syncytiotrophoblast Function

During placental formation, cytotrophoblasts (CTBs) fuse into multinucleate, microvilli-coated syncytiotrophoblasts (STBs), which contact maternal blood, mediating nutrient, metabolite, and gas exchange between mother and fetus, and providing a barrier against fetal infection. Trophoblasts remodel the surrounding extracellular matrix through the secretion of matrix metalloproteinases (MMPs). Maternal obesity and diabetes mellitus can negatively impact fetal development and may impair trophoblast function. We sought to model the impact of metabolic stress on STB function by examining MMP and hormone secretion. The BeWo CTB cell line was syncytialized to STB-like cells with forskolin. Cell morphology was examined by electron microscopy and immunofluorescence; phenotype was further assessed by ELISA and RT-qPCR. STBs were exposed to a metabolic stress cocktail (MetaC: 30 mM glucose, 10 nM insulin, and 0.1 mM palmitic acid). BeWo syncytialization was demonstrated by increased secretion of HCGβ and progesterone, elevated syncytin gene expression (ERVW-1 and ERVFRD-1), loss of tight junctions, and increased surface microvilli. MetaC strongly suppressed syncytin gene expression (ERVW-1 and ERVFRD-1), suppressed HCGβ and progesterone secretion, and altered both MMP-9 and MMP-2 production. Metabolic stress modeling diabetes and obesity altered BeWo STB hormone and MMP production in vitro.

Environmental Toxicant Exposure Paralyzes Human Placental Macrophage Responses to Microbial Threat

Exposure to environmental toxicants (such as dioxins) has been epidemiologically linked to adverse reproductive health outcomes, including placental inflammation and preterm birth. However, the molecular underpinnings that govern these outcomes in gravid reproductive tissues remain largely unclear. Placental macrophages (also known as Hofbauer cells) are crucial innate immune cells that defend the gravid reproductive tract and help promote maternal-fetal tolerance. We hypothesized that exposure to environmental toxicants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) could alter placental macrophage responses to inflammatory insults such as infection. To test this, placental macrophages were cultured in the presence or absence of TCDD and then infected with the perinatal pathogen Group B Streptococcus (GBS). Our results indicate that TCDD is lethal to placental macrophages at and above a 5 nM concentration and that sublethal dioxin exposure inhibits phagocytosis and cytokine production. Taken together, these results indicate that TCDD paralyzes placental macrophage responses to bacterial infection.

Comparison of Published Estimates of the National Prevalence of Iron, Vitamin A, and Zinc Deficiency and Sources of Inconsistencies

Micronutrient deficiencies result in a broad range of adverse health and functional consequences, but the true prevalence of specific deficiencies remains uncertain because limited information is available from nationally representative surveys using recommended biomarkers. The present review compares various reported national deficiency prevalence estimates for nutrients and years where the estimates overlap for individual countries that conducted nationally representative surveys and explores possible reasons for any discrepancies discovered. Nationally representative micronutrient status surveys that were conducted since 2000 among preschool-aged children or women of reproductive age and included assessment of iron, vitamin A, or zinc status based on recognized biomarkers were considered eligible for inclusion, along with any modeled deficiency prevalence estimates for these same countries and years. There was considerable variation across different published prevalence estimates, with larger inconsistencies when the prevalence estimate was based on proxies, such as hemoglobin for iron deficiency and dietary zinc availability for zinc deficiency. Numerous additional methodological issues affected the prevalence estimates, such as which biomarker and what cutoff was used to define deficiency, whether the biomarker was adjusted for inflammation, and what adjustment method was used. For some country-years, the various approaches resulted in fairly consistent prevalence estimates. For other country-years, however, the results differed markedly and changed the conclusions regarding the existence and severity of the micronutrient deficiency as a public health concern. In conclusion, to determine micronutrient status, we consider the assessment of one of the recommended biomarkers in a population representative survey as the best available information. If indicated, results should be adjusted for inflammation and generally acceptable cutoffs should be applied to facilitate comparisons, although individual countries may also apply nationally defined cutoffs to determine when and where to intervene. Global consensus is needed on best practices for presenting survey results and defining the prevalence of deficiency.

Review of intervention products for use in the prevention and control of anemia

Anemia remains a major public health problem, especially in low- and middle-income countries. The World Health Organization recommends several interventions to prevent and manage anemia in vulnerable population groups, including young children, menstruating adolescent girls and women, and pregnant and postpartum women. Daily iron supplementation reduces the risk of anemia in infants, children, and pregnant women, and intermittent iron supplementation reduces anemia risk in menstruating girls and women. Micronutrient powders reduce the risk of anemia in children. Fortifying wheat flour with iron reduces the risk of anemia in the overall population, whereas the effect of fortifying maize flour and rice is still uncertain. Regarding non-nutrition-related interventions, malaria treatment and deworming have been reported to decrease anemia prevalence. Promising interventions to prevent anemia include vitamin A supplementation, multiple micronutrient supplementation for pregnant women, small-quantity lipid-based supplements, and fortification of salt with iodine and iron. Future research could address the efficacy and safety of different iron supplementation formulations, identify the most bioavailable form of iron for fortification, examine adherence to supplementation regimens and fortification standards, and investigate the effectiveness of integrating micronutrient, helminth, and malaria control programs.

Integrating and coordinating programs for the management of anemia across the life course

Anemia is a major global public health concern with a complex etiology. The main determinants are nutritional factors, infection and inflammation, inherited blood disorders, and women's reproductive biology, but the relative role of each varies between settings. Effective anemia programming, therefore, requires evidence-based, data-driven, contextualized multisectoral strategies, with coordinated implementation. Priority population groups are preschool children, adolescent girls, and pregnant and nonpregnant women of reproductive age. Opportunities for comprehensive anemia programming include: (i) bundling interventions through shared delivery platforms, including antenatal care, community-based platforms, schools, and workplaces; (ii) integrating delivery platforms to extend reach; (iii) integrating anemia and malaria programs in endemic areas; and (iv) integrating anemia programming across the life course. Major barriers to effective anemia programming include weak delivery systems, lack of data or poor use of data, lack of financial and human resources, and poor coordination. Systems strengthening and implementation research approaches are needed to address critical gaps, explore promising platforms, and identify solutions to persistent barriers to high intervention coverage. Immediate priorities are to close the gap between access to service delivery platforms and coverage of anemia interventions, reduce subnational coverage disparities, and improve the collection and use of data to inform anemia strategies and programming.

Comprehensive framework for integrated action on the prevention, diagnosis, and management of anemia: An introduction

The World Health Organization (WHO) announced in 2021 a commitment to develop a comprehensive framework for integrated action on the prevention, diagnosis, and management of anemia and to establish an Anaemia Action Alliance to support the implementation of the framework. WHO commissioned four background papers to provide reflections about the most pressing issues to be addressed for accelerating reductions in the prevalence of anemia. Here, we provide a complete vision of the framework.

Accelerating action to reduce anemia: Review of causes and risk factors and related data needs

Anemia is a major public health concern. Young children, menstruating adolescent girls and women, and pregnant women are among the most vulnerable. Anemia is the consequence of a wide range of causes, including biological, socioeconomic, and ecological risk factors. Primary causes include: iron deficiency; inherited red blood cell disorders; infections, such as soil-transmitted helminthiasis, schistosomiasis, and malaria; gynecological and obstetric conditions; and other chronic diseases that lead to blood loss, decreased erythropoiesis, or destruction of erythrocytes. The most vulnerable population groups in low- and middle-income countries are often at the greatest risk to suffer from several of these causes simultaneously as low socioeconomic status is linked with an increased risk of anemia through multiple pathways. Targeted and effective action is needed to prevent anemia. Understanding the causes and risk factors of anemia for different population subgroups within a country guides the design and implementation of effective strategies to prevent and treat anemia. A coordinated approach across various expert groups and programs could make the best use of existing data or could help to determine when newer and more relevant data may need to be collected, especially in countries with a high anemia burden and limited information on the etiology of anemia.

Associations between type of blood collection, analytical approach, mean haemoglobin and anaemia prevalence in population-based surveys: A systematic review and meta-analysis

Background

Previous studies have observed that haemoglobin concentrations can be affected by type of blood collection, analysis methods and device, and that near-in-time population-based surveys report substantially different anaemia prevalence. We investigated whether differences in mean haemoglobin or prevalence of anaemia between near-in-time surveys of the same population were associated with differences in type of blood collection or analytic approach to haemoglobin measurement.

Methods

We systematically identified pairs of population-based surveys that measured haemoglobin in the same population of women of reproductive age (WRA) or preschool-aged children (PSC). Surveys were matched on geographic coverage, urban/rural place of residence, inclusion of pregnant women, time of data collection (within 18 months), and, to the extent feasible, age range. Differences in anaemia prevalence were presented graphically. Random-effects meta-analysis and meta-regression of difference in mean haemoglobin were carried out, with subgroups defined by comparison of type of blood collection and analytic approach within each survey pair.

Results

We included 23 survey pairs from 17 countries for PSC and 17 survey pairs from 11 countries for WRA. Meta-regression indicates that surveys measuring haemoglobin with HemoCue® Hb 301 found higher haemoglobin concentrations than near-in-time surveys using HemoCue® Hb 201+ in non-pregnant women ((NPW); 5.8 g/L (95% confidence interval (CI) = 3.2-8.3) mean difference, n = 5 pairs) and PSC (4.3 g/L (1.4-7.2), n = 6). Surveys collecting venous blood found higher haemoglobin concentrations than near-in-time surveys collecting capillary blood in PSC (3.8 g/L (0.8-6.7), n = 8), but not NPW (0.4 g/L (-1.9-2.8), n = 9).

Conclusions

Because this study is observational, differences in haemoglobin concentrations in near-in-time surveys may be caused by other factors associated with choice of analytic approach or type of blood collected. The source or sources of differences should be clarified to improve use of surveys to prioritize and evaluate public health programs.

Registration

PROSPERO CRD42022296553.

Streptococcus agalactiae cadD alleviates metal stress and promotes intracellular survival in macrophages and ascending infection during pregnancy

Perinatal infection with Streptococcus agalactiae, or Group B Streptococcus (GBS), is associated with preterm birth, neonatal sepsis, and stillbirth. Here, we study the interactions of GBS with macrophages, essential sentinel immune cells that defend the gravid reproductive tract. Transcriptional analyses of GBS-macrophage co-cultures reveal enhanced expression of a gene encoding a putative metal resistance determinant, cadD. Deletion of cadD reduces GBS survival in macrophages, metal efflux, and resistance to metal toxicity. In a mouse model of ascending infection during pregnancy, the ΔcadD strain displays attenuated bacterial burden, inflammation, and cytokine production in gestational tissues. Furthermore, depletion of host macrophages alters cytokine expression and decreases GBS invasion in a cadD-dependent fashion. Our results indicate that GBS cadD plays an important role in metal detoxification, which promotes immune evasion and bacterial proliferation in the pregnant host.

Persistent bacteremia and psoas abscess caused by a lethal toxin-deficient Paeniclostridiumsordellii

We present a case of persistent bacteremia and psoas abscess from Paeniclostridium sordellii without severe symptoms or the classically associated toxic shock syndrome. Further laboratory evaluation demonstrated that the Paeniclostridium sordellii isolate lacked the lethal toxin gene and there was no cytotoxicity to exposed Vero cells.

National, regional, and global estimates of anaemia by severity in women and children for 2000-19: a pooled analysis of population-representative data

BACKGROUND

Anaemia causes health and economic harms. The prevalence of anaemia in women aged 15-49 years, by pregnancy status, is indicator 2.2.3 of the UN Sustainable Development Goals, and the aim of halving the anaemia prevalence in women of reproductive age by 2030 is an extension of the 2025 global nutrition targets endorsed by the World Health Assembly (WHA). We aimed to estimate the prevalence of anaemia by severity for children aged 6-59 months, non-pregnant women aged 15-49 years, and pregnant women aged 15-49 years in 197 countries and territories and globally for the period 2000-19.

METHODS

For this pooled analysis of population-representative data, we collated 489 data sources on haemoglobin distribution in children and women from 133 countries, including 4·5 million haemoglobin measurements. Our data sources comprised health examination, nutrition, and household surveys, accessed as anonymised individual records or as summary statistics such as mean haemoglobin and anaemia prevalence. We used a Bayesian hierarchical mixture model to estimate haemoglobin distributions in each population and country-year. This model allowed for coherent estimation of mean haemoglobin and prevalence of anaemia by severity.

FINDINGS

Globally, in 2019, 40% (95% uncertainty interval [UI] 36-44) of children aged 6-59 months were anaemic, compared to 48% (45-51) in 2000. Globally, the prevalence of anaemia in non-pregnant women aged 15-49 years changed little between 2000 and 2019, from 31% (95% UI 28-34) to 30% (27-33), while in pregnant women aged 15-49 years it decreased from 41% (39-43) to 36% (34-39). In 2019, the prevalence of anaemia in children aged 6-59 months exceeded 70% in 11 countries and exceeded 50% in all women aged 15-49 years in ten countries. Globally in all populations and in most countries and regions, the prevalence of mild anaemia changed little, while moderate and severe anaemia declined in most populations and geographical locations, indicating a shift towards mild anaemia.

INTERPRETATION

Globally, regionally, and in nearly all countries, progress on anaemia in women aged 15-49 years is insufficient to meet the WHA global nutrition target to halve anaemia prevalence by 2030, and the prevalence of anaemia in children also remains high. A better understanding of the context-specific causes of anaemia and quality implementation of effective multisectoral actions to address these causes are needed.

FUNDING

USAID, US Centers for Disease Control and Prevention, and Bill & Melinda Gates Foundation.

Critical assessment of the current indicator for antenatal iron‐containing supplementation coverage: Insights from a mixed‐methods study

Daily consumption of iron‐containing supplements is recommended for all pregnant women but there is no approved global standard indicator for assessing supplementation coverage. Furthermore, the validity of commonly used coverage indicators for iron‐containing supplement consumption is questionable. The WHO–UNICEF Technical Expert Advisory Group on Nutrition Monitoring, and partners, have systematically worked to identify a feasible and valid indicator of iron‐containing supplement coverage for reporting by countries. In 2019, we conducted key informant interviews with respondents in eight countries, fielded an online survey (in three languages using SurveyMonkey) to which 142 nutrition professionals from 52 countries responded, and used Demographic and Health Surveys (DHS) data from four countries to assess determinants of the quality of iron‐containing supplement coverage data. Less than half (45%) of online survey respondents were satisfied with the current methods for collecting iron‐containing supplement coverage data in their context. Recommended changes by study respondents include recall period <5 years, adding questions about counselling, including other beneficiary groups, and assessing supply chain functionality. The DHS analysis suggested an association between time since pregnancy and data quality. Data heaping on multiples of 30 was observed in 40%–75% of data. There is a clear demand for a revised indicator and measurement guidance for coverage of iron‐containing supplementation during pregnancy. Future research should continue the development and validation of a global indicator, to more precisely validate the quality of recall data, including the distinction between distribution and consumption using various question formulations.

Health and nutrition professionals have described concerns with current methods for reporting coverage of daily iron‐containing supplementation in pregnant women.

The long recall period (5 years) of commonly used iron‐containing supplement consumption indicators calls into question the validity of these indicators.

Our study indicates that there is demand for a revised indicator and guidance for data collection.

Group B Streptococcus cpsE Is Required for Serotype V Capsule Production and Aids in Biofilm Formation and Ascending Infection of the Reproductive Tract during Pregnancy

Group B Streptococcus (GBS) is an encapsulated Gram-positive pathogen that causes ascending infections of the reproductive tract during pregnancy. The capsule of this organism is a critical virulence factor that has been implicated in a variety of cellular processes to promote pathogenesis. Primarily comprised of carbohydrates, the GBS capsule and its synthesis is driven by the capsule polysaccharide synthesis (cps) operon. The cpsE gene within this operon encodes a putative glycosyltransferase that is responsible for the transfer of a Glc-1-P from UDP-Glc to an undecaprenyl lipid molecule. We hypothesized that the cpsE gene product is important for GBS virulence and ascending infection during pregnancy. Our work demonstrates that a GBS cpsE mutant secretes fewer carbohydrates, has a reduced capsule, and forms less biofilm than the wild-type parental strain. We show that, compared to the parental strain, the ΔcpsE deletion mutant is more readily taken up by human placental macrophages and has a significantly attenuated ability to invade and proliferate in the mouse reproductive tract. Taken together, these results demonstrate that the cpsE gene product is an important virulence factor that aids in GBS colonization and invasion of the gravid reproductive tract.

Self-management of iron and folic acid supplementation during pre-pregnancy, pregnancy and postnatal periods: a systematic review

Introduction

While the use of folic acid pre-pregnancy and iron and folic acid (IFA) during pregnancy and postnatal have been demonstrated to be effective and are recommended interventions by WHO, ensuring individuals adhere to the supplementation regimen can be a challenge. Self-care interventions that support an individual’s ability to promote their own health with or without the support of health workers could help promote the uptake and adherence to supplementation. This systematic review assessed the evidence around self-management of IFA or folic acid supplementation accessed over-the-counter during pre-pregnancy, pregnancy and postnatal periods.

Methods

Peer-reviewed studies were included if they compared self-management of IFA or folic acid supplementation with health worker-initiated supplement use on maternal and/or fetal and newborn health outcomes, end-users’ or health workers’ values and preferences, or cost and/or cost-effectiveness. We searched PubMed, CINAHL, LILACS and EMBASE for articles published through November 2020, hand-searched clinical trial registries, reviewed databases and contacted experts in the field. Abstract screening and full-text review were conducted independently by two reviewers.

Results

Overall, 2344 results were identified, and 28 studies were identified for full-text review. All studies were excluded, as they were not primary research, lacked the outcomes of interest, lacked specificity in supplement type, and/or lacked a comparison group.

Conclusion

No evidence was identified that distinguishes self-management of folic acid supplements pre-pregnancy and of IFA supplements during pregnancy and postnatal, highlighting a gap in our current understanding of self-care related to dietary supplementation in pregnancy. The findings of this review identify an area for further research to support the current movement towards self-care interventions as an added choice to help individuals more fully attain their reproductive health and rights.

Systematic review registration number

PROSPERO CRD42020205548

Prostaglandin I2 signaling licenses Treg suppressive function and prevents pathogenic reprogramming

Tregs restrain both the innate and adaptive immune systems to maintain homeostasis. Allergic airway inflammation, characterized by a Th2 response that results from a breakdown of tolerance to innocuous environmental antigens, is negatively regulated by Tregs. We previously reported that prostaglandin I2 (PGI2) promoted immune tolerance in models of allergic inflammation; however, the effect of PGI2 on Treg function was not investigated. Tregs from mice deficient in the PGI2 receptor IP (IP KO) had impaired suppressive capabilities during allergic airway inflammatory responses compared with mice in which PGI2 signaling was intact. IP KO Tregs had significantly enhanced expression of immunoglobulin-like transcript 3 (ILT3) compared with WT Tregs, which may contribute to the impairment of the IP KO Treg's ability to suppress Th2 responses. Using fate-mapping mice, we reported that PGI2 signaling prevents Treg reprogramming toward a pathogenic phenotype. PGI2 analogs promoted the differentiation of naive T cells to Tregs in both mice and humans via repression of β-catenin signaling. Finally, a missense variant in IP in humans was strongly associated with chronic obstructive asthma. Together, these data support that PGI2 signaling licenses Treg suppressive function and that PGI2 is a therapeutic target for enhancing Treg function.

Antibacterial and Anti-biofilm Activity of the Human Breast Milk Glycoprotein Lactoferrin against Group B Streptococcus

Group B Streptococcus (GBS) is an encapsulated Gram-positive human pathogen that causes invasive infections in pregnant hosts and neonates, as well as immunocompromised individuals. Colonization of the human host requires the ability to adhere to mucosal surfaces and circumnavigate the nutritional challenges and antimicrobial defenses associated with the innate immune response. Biofilm formation is a critical process to facilitate GBS survival and establishment of a replicative niche in the vertebrate host. Previous work has shown that the host responds to GBS infection by producing the innate antimicrobial glycoprotein lactoferrin, which has been implicated in repressing bacterial growth and biofilm formation. Additionally, lactoferrin is highly abundant in human breast milk and could serve a protective role against invasive microbial pathogens. This study demonstrates that human breast milk lactoferrin has antimicrobial and anti-biofilm activity against GBS and inhibits its adherence to human gestational membranes. Together, these results indicate that human milk lactoferrin could be used as a prebiotic chemotherapeutic strategy to limit the impact of bacterial adherence and biofilm formation on GBS-associated disease outcomes.

Metabolism of Neonatal Vitamin A Supplementation: A Systematic Review

A systematic review was conducted to summarize the absorption, transport, storage, and metabolism of oral neonatal vitamin A supplementation (NVAS). This review focused specifically on the neonatal period (first 28 d of life for humans) to inform guidance by WHO on recommendations related to NVAS. A systematic search of international and regional databases was conducted. Inclusion criteria were human or animal studies that gave oral vitamin A as a single or limited number of doses to apparently healthy neonates. Studies evaluating fortification or food-based approaches, dosing with retinoic acid, or studies of neonatal models of disease were excluded. The search retrieved 8847 unique records. After screening by title and abstract, 88 were screened using the full text, and 35 records met inclusion criteria: 13 human and 22 animal studies. Studies indicate that high-dose NVAS is absorbed well by neonates, typically mirroring fat absorption. Doses were primarily stored in the liver and transiently increased in the lung, kidney, spleen, adrenal glands, brain, skin, and adipose tissue, generally with a dose-response. Serum retinol and retinyl esters also transiently increased following NVAS. Although minimal acute adverse effects are noted, there is a lack of data supporting NVAS for improving organ maturation or sustained delivery to target organs. Research gaps include the physiological effects of the short-term increase of vitamin A concentrations in extrahepatic tissues, or whether there are unknown adverse effects over time.

Cytotrophoblasts suppress macrophage-mediated inflammation through a contact-dependent mechanism

PROBLEM

Gestational membrane (GM) infection provokes inflammation and can result in preterm prelabor rupture of membranes (PPROM). The choriodecidual layer of the GM includes decidual stromal cells (DSC), cytotrophoblasts (CTB), and macrophages (Mφ). Our laboratory has previously shown that DSCs suppress Mφ TNF-α production through secreted prostaglandin E₂ . We hypothesized that CTBs would also inhibit Mφ cytokine expression through secreted mediators.

METHOD OF STUDY

THP.1 Mφ-like cells with an NF-κB reporter construct or human blood monocyte-derived Mφ were co-cultured with the Jeg3 CTB cell line or primary human CTBs and challenged with group B streptococcus (GBS) or Toll-like receptor (TLR) agonists. Conditioned medium generated from CTB cultures was applied to Mφ cultures before infection or treatment. Alternatively, CTBs were co-incubated with, but physically separated from, Mφ and GBS or TLR-stimulated. NF-κB was assessed via alkaline phosphatase assay, and proinflammatory mediators were assessed by qRT-PCR and ELISA.

RESULTS

CTBs suppressed GBS- or TLR-stimulated Mφ NF-κB activity, and TNF-α and MMP9 production. Direct physical contact between CTBs and Mφ was required for full immunosuppression. Immunosuppression could be overcome by increasing the ratio of Mφ to CTB.

CONCLUSIONS

CTBs limit Mφ NF-κB activation and production of TNF-α and MMP9 through an as-yet unknown, cell-to-cell contact-mediated mechanism. This suppression is distinct from the PGE₂ -mediated Mφ TNF-α suppression by DSC, suggesting that DSCs and CTBs regulate Mφ inflammation through distinct mechanisms. How Mφ integrates these signals in an intact GM will be paramount to determining causes and prevention of PPROM.

Palmitate induces apoptotic cell death and inflammasome activation in human placental macrophages

INTRODUCTION

There is an increasing prevalence of non-communicable diseases worldwide. Metabolic diseases such as obesity and gestational diabetes mellitus (GDM) increasingly affect women during pregnancy, which can harm pregnancy outcomes and the long-term health and wellbeing of exposed offspring. Both obesity and GDM have been associated with proinflammatory effects within the placenta, the critical organ governing fetal development.

METHODS

The purpose of these studies was to model, in vitro, the effects of metabolic stress (high levels of glucose, insulin and saturated lipids) on placental macrophage biology, since these cells are the primary innate immune phagocyte within the placenta with roles in governing maternofetal immune tolerance and antimicrobial host defense. Macrophages were isolated from the villous core of term, human placentae delivered through nonlaboring, elective Cesarean sections and exposed to combinations of elevated glucose (30 mM), insulin (10 nM) and the saturated lipid palmitic acid (palmitate, 0.4 mM).

RESULTS

We found that palmitate alone induced the activation of the nucleotide-binding oligomerization domain-like receptor (NLR) Family Pyrin Domain Containing 3 (NLRP3) inflammasome in placental macrophages, which was associated with increased interleukin 1 beta release and an increase in apoptotic cell death. Glucose and insulin neither provoked these effects nor augmented the impact of palmitate itself.

DISCUSSION

Our findings confirm an impact of saturated fat on placental macrophage immune activation and could be relevant to the impact of metabolic stress in vivo.

Instrumenting a Fetal Membrane on a Chip as Emerging Technology for Preterm Birth Research

Preterm birth (PTB) is clinically defined as process of giving birth before 37 weeks of gestation and is a leading cause of death among neonates and children under the age of five. Prematurity remains a critical issue in developed countries, yet our understanding of the pathophysiology of PTB remains largely unknown. Among pregnancy complications, subclinical infections such as chorioamnionitis (CAM) are implicated in up to 70% of PTB cases. Specifically, CAM is characterized by the infection of the fetal membranes that surround the developing fetus and extend from the placenta, and is often associated with preterm, premature rupture of the fetal membranes (PPROM). The fetal membrane plays a key structural role in maintaining the fetal and maternal compartments of the gravid uterus. However, our understanding of the mechanisms of PPROM and the spatio-temporal progress of CAM remains vastly unknown. A lack of human-derived models have hindered our understanding of the mechanism that govern spontaneous PTB. Thus, in this short review, we discuss the emerging microfabrication technologies, specifically, organ-on-chip (OoCs) models, that seek to recapitulate the cellular and molecular context of the gestational membranes in vitro. These models show promise to facilitate the investigation of pathologic mechanisms that drive these disease conditions by mimicking the interactive contribution of the major cell types that make up the microenvironment of the fetal membrane and enable high throughput screening. Herein, we histologically characterize the microenvironment of the fetal membrane as a metric for scaling to recapitulate the functional components of the human fetal membrane. We review the current OoC models of the gravid uterus and conceptualize an "Instrumented Fetal Membrane on a Chip" (IFMOC) design as a prototype for PPROM and CAM research. Lastly, we discuss further applications of these OoC models for toxicological or pharmacological screening and personalized medicine. Fetal membrane OoCs offer an innovative and valuable platform to explore complex interactions between multiple drug types, toxic substances, and/or pathogenic microbes and their potential impacts on pregnancy outcomes. Further work will be required by integrating technological and analytical capabilities in order to characterize the fetal membrane microenvironment for preterm birth research.

A Nonhemolytic Group B Streptococcus Strain Exhibits Hypervirulence

Group B streptococci (GBS) are Gram-positive bacteria that are a leading cause of neonatal infections. Most invasive isolates are β-hemolytic, and hemolytic activity is critical for GBS virulence. Although nonhemolytic GBS strains are occasionally isolated, they are often thought to be virulence attenuated. In this study, we show that a nonhemolytic GBS strain (GB37) isolated from a septic neonate exhibits hypervirulence. Substitution of tryptophan to leucine (W297L) in the sensor histidine kinase CovS results in constitutive kinase signaling, leading to decreased hemolysis and increased activity of the GBS hyaluronidase, HylB. These results describe how nonpigmented and nonhemolytic GBS strains can exhibit hypervirulence.

Protein kinase D mediates inflammatory responses of human placental macrophages to Group B Streptococcus

PROBLEM

During pregnancy, Group B Streptococcus (GBS) can infect fetal membranes to cause chorioamnionitis, resulting in adverse pregnancy outcomes. Macrophages are the primary resident phagocyte in extraplacental membranes. Protein kinase D (PKD) was recently implicated in mediating pro-inflammatory macrophage responses to GBS outside of the reproductive system. This work aimed to characterize the human placental macrophage inflammatory response to GBS and address the extent to which PKD mediates such effects.

METHOD

Primary human placental macrophages were infected with GBS in the presence or absence of a specific, small molecule PKD inhibitor, CRT 0066101. Macrophage phenotypes were characterized by evaluating gene expression, cytokine release, assembly of the NLRP3 inflammasome, and NFκB activation.

RESULTS

GBS evoked a strong inflammatory phenotype characterized by the release of inflammatory cytokines (TNFα, IL-1β, IL-6 (P ≤ 0.05), NLRP3 inflammasome assembly (P ≤ 0.0005), and NFκB activation (P ≤ 0.05). Pharmacological inhibition of PKD suppressed these responses, newly implicating a role for PKD in mediating immune responses of primary human placental macrophages to GBS.

CONCLUSION

PKD plays a critical role in mediating placental macrophage inflammatory activation in response to GBS infection.

Fetal Membrane Organ-On-Chip: An Innovative Approach to Study Cellular Interactions

OBJECTIVE:

Fetal membranes, a vital component that helps maintain pregnancy and contribute to parturition signaling, are often studied in segments due to its structural complexity. Transwells are traditionally used to study cell interactions; however, their usefulness is limited. To overcome these difficulties, a fetal membrane-organ-on-chip (FM-OO-C) was created to study interactive properties of amnion epithelial cells (AECs) and decidual cells compared to transwell systems.

METHODS:

Primary AECs and decidual cells from term, nonlaboring fetal membranes were cultured in a 2-chamber (AEC/decidual cell) FM-OO-C device and sandwiched between a semipermeable membrane. Cells were treated with cigarette smoke extract (CSE) or dioxin, and membrane permeability and cellular senescence were measured after 48 hours. The same experiments were conducted in transwells for comparisons.

RESULTS:

Compared to transwell cultures, FM-OO-C model produced better membrane permeability readings regardless of the side of treatment or time point. Membrane permeabilization was higher in AECs directly treated with CSE (1.6 fold) compared to similar treatment on the decidual side (1.2 fold). In FM-OO-C, treatments forced changes between cellular layers. This was evident when CSE and dioxin-induced senescence on one side of the chamber produced similar changes on the opposite side. This effect was minimal in the transwell system.

CONCLUSION:

The controlled environment of an FM-OO-C allows for improved signal propagation between cells by minimizing noise and highlighting the small changes between treatments that cannot be seen in conventional transwell devices. Fetal membrane-organ-on-chip provides a better interaction between cell types that can be used to study fetal-maternal signaling during pregnancy in future studies.

Nonsteroidal Anti-inflammatory Drugs Alter the Microbiota and Exacerbate Clostridium difficile Colitis while Dysregulating the Inflammatory Response

Clostridium difficile infection (CDI) is a major public health threat worldwide. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with enhanced susceptibility to and severity of CDI; however, the mechanisms driving this phenomenon have not been elucidated. NSAIDs alter prostaglandin (PG) metabolism by inhibiting cyclooxygenase (COX) enzymes. Here, we found that treatment with the NSAID indomethacin prior to infection altered the microbiota and dramatically increased mortality and the intestinal pathology associated with CDI in mice. We demonstrated that in C. difficile-infected animals, indomethacin treatment led to PG deregulation, an altered proinflammatory transcriptional and protein profile, and perturbed epithelial cell junctions. These effects were paralleled by increased recruitment of intestinal neutrophils and CD4⁺ cells and also by a perturbation of the gut microbiota. Together, these data implicate NSAIDs in the disruption of protective COX-mediated PG production during CDI, resulting in altered epithelial integrity and associated immune responses.IMPORTANCEClostridium difficile infection (CDI) is a spore-forming anaerobic bacterium and leading cause of antibiotic-associated colitis. Epidemiological data suggest that use of nonsteroidal anti-inflammatory drugs (NSAIDs) increases the risk for CDI in humans, a potentially important observation given the widespread use of NSAIDs. Prior studies in rodent models of CDI found that NSAID exposure following infection increases the severity of CDI, but mechanisms to explain this are lacking. Here we present new data from a mouse model of antibiotic-associated CDI suggesting that brief NSAID exposure prior to CDI increases the severity of the infectious colitis. These data shed new light on potential mechanisms linking NSAID use to worsened CDI, including drug-induced disturbances to the gut microbiome and colonic epithelial integrity. Studies were limited to a single NSAID (indomethacin), so future studies are needed to assess the generalizability of our findings and to establish a direct link to the human condition.

Investigation of the Role That NADH Peroxidase Plays in Oxidative Stress Survival in Group B Streptococcus

Macrophages play an important role in defending the host against infections by engulfing pathogens and containing them inside the phagosome, which consists of a harsh microbicidal environment. However, many pathogens have developed mechanisms to survive inside macrophages despite this challenge. Group B Streptococcus (GBS), a leading cause of sepsis and meningitis in neonates, is one such pathogen that survives inside macrophages by withstanding phagosomal stress. Although a few key intracellular survival factors have been identified, the mechanisms by which GBS detoxifies the phagosome are poorly defined. Transcriptional analysis during survival inside macrophages revealed strong upregulation of a putative NADH peroxidase (npx) at 1 and 24 h post-infection. A deletion mutant of npx (Δnpx) was more susceptible to killing by a complex in vitro model of multiple phagosomal biochemical/oxidant stressors or by hydrogen peroxide alone. Moreover, compared to an isogenic wild type GBS strain, the Δnpx strain demonstrated impaired survival inside human macrophages and a reduced capacity to blunt macrophage reactive oxygen species (ROS) production. It is therefore likely that Npx plays a role in survival against ROS production in the macrophage. A more thorough understanding of how GBS evades the immune system through survival inside macrophages will aid in development of new therapeutic measures.

Global folate status in women of reproductive age: a systematic review with emphasis on methodological issues

Inadequate folate status in women of reproductive age (WRA) can lead to adverse health consequences of public health significance, such as megaloblastic anemia (folate deficiency) and an increased risk of neural tube defect (NTD)-affected pregnancies (folate insufficiency). Our review aims to evaluate current data on folate status of WRA. We queried eight databases and the World Health Organization Micronutrients Database, identifying 45 relevant surveys conducted between 2000 and 2014 in 39 countries. Several types of folate assays were used in the analysis of blood folate, and many surveys used folate cutoffs not matched to the assay. To allow better comparisons across surveys, we attempted to account for these differences. The prevalence of folate deficiency was >20% in many countries with lower income economies but was typically <5% in countries with higher income economies. Only 11 surveys reported the prevalence of folate insufficiency, which was >40% in most countries. Overall, folate status data for WRA globally are limited and must be carefully interpreted due to methodological issues. Future surveys would benefit from using the microbiologic assay to assess folate status, along with assay-matched cutoffs to improve monitoring and evaluation of folic acid interventions, thus informing global efforts to prevent NTDs.

Decidual stromal cell-derived PGE2 regulates macrophage responses to microbial threat

PROBLEM

Bacterial chorioamnionitis causes adverse pregnancy outcomes, yet host-microbial interactions are not well characterized within gestational membranes. The decidua, the outermost region of the membranes, is a potential point of entry for bacteria ascending from the vagina to cause chorioamnionitis. We sought to determine whether paracrine communication between decidual stromal cells and macrophages shaped immune responses to microbial sensing.

METHOD OF STUDY

Decidual cell-macrophage interactions were modeled in vitro utilizing decidualized, telomerase-immortalized human endometrial stromal cells (dTHESCs) and phorbol ester-differentiated THP-1 macrophage-like cells. The production of inflammatory mediators in response to LPS was monitored by ELISA for both cell types, while phagocytosis of bacterial pathogens (Escherichia coli and Group B Streptococcus (GBS)) was measured in THP-1 cells or primary human placental macrophages. Diclofenac, a non-selective cyclooxygenase inhibitor, and prostaglandin E₂ (PGE₂ ) were utilized to interrogate prostaglandins as decidual cell-derived paracrine immunomodulators. A mouse model of ascending chorioamnionitis caused by GBS was utilized to assess the colocalization of bacteria and macrophages in vivo and assess PGE₂ production.

RESULTS

In response to LPS, dTHESC and THP-1 coculture demonstrated enhancement of most inflammatory mediators, but a potent suppression of macrophage TNF-α generation was observed. This appeared to reflect a paracrine-mediated effect of decidual cell-derived PGE₂ . In mice with GBS chorioamnionitis, macrophages accumulated at sites of bacterial invasion with increased PGE₂ in amniotic fluid, suggesting such paracrine effects might hold relevance in vivo.

CONCLUSION

These data suggest key roles for decidual stromal cells in modulating tissue responses to microbial threat through release of PGE₂ .

Variation in Macrophage Phagocytosis of Streptococcus agalactiae Does Not Reflect Bacterial Capsular Serotype, Multilocus Sequence Type or Association with Invasive Infection

Background: Group B Streptococcus(GBS) is an encapsulated Gram-positive coccus that is an important cause of infections in adults with chronic medical conditions, pregnant women, and neonates. GBS causes a range of clinical syndromes, from asymptomatic colonization to deep-seated invasive and highly lethal infections. Macrophages are important sentinels of innate immunity, protecting host tissues from infection when bacteria advance beyond cutaneous or mucosal barriers. We hypothesized that the capacity for macrophages to phagocytose unopsonized GBS would vary across distinct clinical strains, and such differences would reflect serotype diversity.Methods: A high-throughput screen using the phorbol ester-differentiated THP-1 macrophage-like human cell line was used to quantify phagocytosis of a diverse group of 35 different human clinical isolates of GBS representing a wide variety of capsular serotypes. Validation studies were conducted using human primary phagocytes.Results: Phagocytosis of GBS differed widely across clinical isolates but this was not related to capsular serotype, genetic sequence type, pilus type, or clinical source of the GBS isolate (colonizing or invasive strain).Conclusions: Structural and/or biochemical differences among diverse GBS strains are reflected in a diverse capacity for macrophages to ingest them through non-opsonic phagocytosis. Mechanisms explaining these differences are not clear.Keywords: Neonatal sepsis; innate immunity; macrophages; Gram-positive bacteria; diabetes

The PathLink Acquired Gestational Tissue Bank: Feasibility of Project PLACENTA

BACKGROUND

The Vanderbilt Institute for Clinical and Translational Research piloted the development of Project PLACENTA (PathLink Acquired gEstatioNal Tissue bAnk). This project investigated the feasibility of a fresh gestational tissue biobank, which provides tissue linked to electronic medical records for investigators interested in maternal-fetal health.

METHODS

We developed a pipeline for collection of placental tissue from Labor and Delivery within approximately 30 minutes of delivery. An email alert was developed, to signal delivery, with the ability to specifically flag patients with certain phenotypic traits. Once collected, 4 to 8 mm punch biopsy cores were snap frozen and subsequently used for DNA, RNA and protein extraction. Tissue was also collected for Formalin Fixed Paraffin Embedded (FFPE) histology, flow cytometry, and quality control measures.

RESULTS

Of 60 deliveries using the email notification system, 25 (42%) were sent to Pathology or assigned to other research protocols and were not available for collection, 10 (16%) were discarded prior to arrival at Labor and Delivery, and 25 (42%) were available for collection. Twenty placentas were collected and averaged 38 minutes per collection. DNA extraction yielded an average of 53 µg/µl per sample and RNA extraction yielded 679 ng/µl on average per sample. Proteomic studies showed no degradation of protein, abundant and similar quantities of protein across samples and differentiation between the amnion, decidua, and villi. Histological studies showed good quality for interpretation and occasional pathology including multifocal chronic villitis, meconium laden macrophages, and Stage 2 acute chorioamnionitis. Flow cytometry demonstrated good cell viability after isolation.

Assessment of iron status in settings of inflammation: challenges and potential approaches

The determination of iron status is challenging when concomitant infection and inflammation are present because of confounding effects of the acute-phase response on the interpretation of most iron indicators. This review summarizes the effects of inflammation on indicators of iron status and assesses the impact of a regression analysis to adjust for inflammation on estimates of iron deficiency (ID) in low- and high-infection-burden settings. We overviewed cross-sectional data from 16 surveys for preschool children (PSC) (n = 29,765) and from 10 surveys for nonpregnant women of reproductive age (WRA) (n = 25,731) from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project. Effects of C-reactive protein (CRP) and α1-acid glycoprotein (AGP) concentrations on estimates of ID according to serum ferritin (SF) (used generically to include plasma ferritin), soluble transferrin receptor (sTfR), and total body iron (TBI) were summarized in relation to infection burden (in the United States compared with other countries) and population group (PSC compared with WRA). Effects of the concentrations of CRP and AGP on SF, sTfR, and TBI were generally linear, especially in PSC. Overall, regression correction changed the estimated prevalence of ID in PSC by a median of +25 percentage points (pps) when SF concentrations were used, by -15 pps when sTfR concentrations were used, and by +14 pps when TBI was used; the estimated prevalence of ID in WRA changed by a median of +8 pps when SF concentrations were used, by -10 pps when sTfR concentrations were used, and by +3 pps when TBI was used. In the United States, inflammation correction was done only for CRP concentrations because AGP concentrations were not measured; regression correction for CRP concentrations increased the estimated prevalence of ID when SF concentrations were used by 3 pps in PSC and by 7 pps in WRA. The correction of iron-status indicators for inflammation with the use of regression correction appears to substantially change estimates of ID prevalence in low- and high-infection-burden countries. More research is needed to determine the validity of inflammation-corrected estimates, their dependence on the etiology of inflammation, and their applicability to individual iron-status assessment in clinical settings.

Macrophage Extracellular Traps: A Scoping Review

Tissue macrophages are derived from either circulating blood monocytes that originate in the bone marrow, or embryonic precursors that establish residence in tissues and are maintained independent of bone marrow progenitors. Macrophages perform diverse functions including tissue repair, the maintenance of homeostasis, and immune regulation. Recent studies have demonstrated that macrophages produce extracellular traps (ETs). ETs are an immune response by which a cell undergoes "ETosis" to release net-like material, with strands composed of cellular DNA that is studded with histones and cellular proteins. ETs are thought to immobilize and kill microorganisms, but also been implicated in disease pathology including aseptic inflammation and autoimmune disease. We conducted a scoping review to define what is known from the existing literature about the ETs produced by monocytes or macrophages. The results suggest that macrophage ETs (METs) are produced in response to various microorganisms and have similar features to neutrophil ETs (NETs), in that METs are produced by a unique cell death program (METosis), which results in release of fibers composed of DNA and studded with cellular proteins. METs function to immobilize and kill some microorganisms, but may also play a role in disease pathology.

Placental pericytes and cytomegalovirus infectivity: Implications for HCMV placental pathology and congenital disease

PROBLEM

Placental pericytes are essential for placental microvascular function, stability, and integrity. Mechanisms of human cytomegalovirus (HCMV) pathogenesis incorporating placental pericytes are unknown.

METHOD OF STUDY

HCMV-infected placental tissue was stained by dual-labeled immunohistochemistry. Primary placental pericytes, cytotrophoblasts, and villous fibroblasts were exposed to HCMV; and infectivity was analyzed by microscopy and immunofluorescence. Cytokine expression was examined by Luminex assay. A HCMV-GFP recombinant virus was used to examine replication kinetics.

RESULTS

Immunohistochemistry showed HCMV in trophoblast and the villous core with T-cell and macrophage infiltration. Primary HCMV isolate from a patient (SBCMV)- infected pericytes showed dysregulation of proinflammatory and angiogenic cytokines when compared to control cells. A tri-cell model of the villous floor showed a unique expression profile. Finally, we show pericytes infected in vivo with HCMV in placental tissue from a congenitally infected child.

CONCLUSION

Placental pericytes support HCMV replication, inducing proinflammatory and angiogenic cytokines that likely contribute to viral dissemination, placenta inflammation, and dysregulation of placental angiogenesis.

Group B Streptococcus infection induces M1-like activation in human placental and mouse decidual macrophages

Group B Streptococcus (GBS), a vaginal colonizing gram-positive bacterium, is a leading cause of neonatal death and sepsis. How GBS evades macrophage defenses in the gravid uterus is not yet known. In response to stimuli, macrophages are activated along a spectrum known as polarization ranging from classically-activated, pro-inflammatory “M1” to alternatively-activated anti-inflammatory “M2” macrophages. These activation states can contribute to disease pathogenesis. This study aims to define changes in macrophage activation in response to GBS infection. Human monocyte derived macrophages (MDMs) were infected with GBS or polarized in vitro with M1 (IFNγ/LPS) or M2 (IL-4 or IL-10) stimuli. Placental macrophages (PMs) were infected with GBS or treated with IFNγ/LPS. To mimic human ascending vaginal infection in vivo, C57BL/6 mice were inoculated vaginally with GBS at day E13.5 for 48h. Subsequently, decidual macrophages were isolated and analyzed for polarization markers via flow cytometry and tissues were used for histology. Resulting phenotypes were characterized using qRT-PCR, ELISA, and flow cytometry. In MDMs, GBS upregulated M1 genes (CCR7, CD80) and downregulated M2 genes (CD209, CD163). GBS increased the release of M1 cytokines (TNFα, IL-1β) in MDMs and PMs. PM surface expression of M1 markers (CCR7, CD80) increased while M2 markers (CD206, CD163, CD209) decreased. Mouse decidual macrophage surface expression of CD206 was downregulated while CD11c exhibited little change. Our results suggest that GBS may induce M1 activation in both human and mouse models. These studies provide new insights into the role of macrophage activation in GBS pathogenesis.

Studies supported by NIH NIAID Training Grant 5T32AI007281-27.

Prostaglandin I2 -orchestrates regulatory and effector T cell–mediated autoimmunity

Tregs maintain tolerance and prevent autoimmune disease by inhibiting T cell activation. There is extensive interest in the application of Tregs in transplantation, autoimmune diseases, and allergy. Our group and others have shown that prostacyclin I2 (PGI2) signaling through the I prostanoid (IP) receptor inhibits allergic airway inflammation. However, it remains unknown whether PGI2 regulates Tregs and Treg-mediated inflammation. We hypothesized that PGI2 skews the immunological balance towards tolerance and away from inflammation. To determine whether PGI2 mediates systemic tolerance, we performed whole animal histopathology on aged WT and IP KO mice. PGI2 protected against autoimmune manifestations including splenomegaly, perivascular-bronchiolar lymphocytic cuffing, and epicarditis that developed in aged IP KO mice. Endogenous PGI2 also promoted Treg Foxp3 expression, suppressive function, and polarization. PGI2 concurrently decreased Teff proliferation and increased Teff susceptibility to Treg-mediated suppression. These studies are the first to show that PGI2 protects against autoimmunity and may represent a novel treatment strategy for Treg-mediated diseases.

Vitamin A Supplementation Programs and Country-Level Evidence of Vitamin A Deficiency

Vitamin A supplementation (VAS) programs targeted at children aged 6–59 months are implemented in many countries. By improving immune function, vitamin A (VA) reduces mortality associated with measles, diarrhea, and other illnesses. There is currently a debate regarding the relevance of VAS, but amidst the debate, researchers acknowledge that the majority of nationally-representative data on VA status is outdated. To address this data gap and contribute to the debate, we examined data from 82 countries implementing VAS programs, identified other VA programs, and assessed the recentness of national VA deficiency (VAD) data. We found that two-thirds of the countries explored either have no VAD data or data that were >10 years old (i.e., measured before 2006), which included twenty countries with VAS coverage ≥70%. Fifty-one VAS programs were implemented in parallel with at least one other VA intervention, and of these, 27 countries either had no VAD data or data collected in 2005 or earlier. To fill these gaps in VAD data, countries implementing VAS and other VA interventions should measure VA status in children at least every 10 years. At the same time, the coverage of VA interventions can also be measured. We identified three countries that have scaled down VAS, but given the lack of VA deficiency data, this would be a premature undertaking in most countries without appropriate status assessment. While the global debate about VAS is important, more attention should be directed towards individual countries where programmatic decisions are made.

Staphylococcus aureus Infection of Human Gestational Membranes Induces Bacterial Biofilm Formation and Host Production of Cytokines

Staphylococcus aureus, a metabolically flexible gram-positive pathogen, causes infections in a variety of tissues. Recent evidence implicates S. aureus as an emerging cause of chorioamnionitis and premature rupture of membranes, which are associated with preterm birth and neonatal disease. We demonstrate here that S. aureus infects and forms biofilms on the choriodecidual surface of explanted human gestational membranes. Concomitantly, S. aureus elicits the production of proinflammatory cytokines, which could ultimately perturb maternal-fetal tolerance during pregnancy. Therefore, targeting the immunological response to S. aureus infection during pregnancy could attenuate disease among infected individuals, especially in the context of antibiotic resistance.

Group B Streptococcus Induces Neutrophil Recruitment to Gestational Tissues and Elaboration of Extracellular Traps and Nutritional Immunity

Streptococcus agalactiae, or Group B Streptococcus (GBS), is a gram-positive bacterial pathogen associated with infection during pregnancy and is a major cause of morbidity and mortality in neonates. Infection of the extraplacental membranes surrounding the developing fetus, a condition known as chorioamnionitis, is characterized histopathologically by profound infiltration of polymorphonuclear cells (PMNs, neutrophils) and greatly increases the risk for preterm labor, stillbirth, or neonatal GBS infection. The advent of animal models of chorioamnionitis provides a powerful tool to study host-pathogen relationships in vivo and ex vivo. The purpose of this study was to evaluate the innate immune response elicited by GBS and evaluate how antimicrobial strategies elaborated by these innate immune cells affect bacteria. Our work using a mouse model of GBS ascending vaginal infection during pregnancy reveals that clinically isolated GBS has the capacity to invade reproductive tissues and elicit host immune responses including infiltration of PMNs within the choriodecidua and placenta during infection, mirroring the human condition. Upon interacting with GBS, murine neutrophils elaborate DNA-containing extracellular traps, which immobilize GBS and are studded with antimicrobial molecules including lactoferrin. Exposure of GBS to holo- or apo-forms of lactoferrin reveals that the iron-sequestration activity of lactoferrin represses GBS growth and viability in a dose-dependent manner. Together, these data indicate that the mouse model of ascending infection is a useful tool to recapitulate human models of GBS infection during pregnancy. Furthermore, this work reveals that neutrophil extracellular traps ensnare GBS and repress bacterial growth via deposition of antimicrobial molecules, which drive nutritional immunity via metal sequestration strategies.

Applying inappropriate cutoffs leads to misinterpretation of folate status in the US population

BACKGROUND

Folate cutoffs for risk of deficiency compared with possible deficiency were originally derived differently (experimental compared with epidemiologic data), and their interpretations are different. The matching of cutoffs derived from one assay with population-based data derived from another assay requires caution.

OBJECTIVE

We assessed the extent of folate-status misinterpretation with the use of inappropriate cutoffs.

DESIGN

In the cross-sectional NHANES, serum and red blood cell (RBC) folate were first measured with the use of a radioprotein-binding assay (RPBA) (1988-2006) and, afterwards, with the use of a microbiologic assay (2007-2010). We compared prevalence estimates for assay-matched cutoffs (e.g., with the use of an RPBA cutoff with RPBA data) and assay-mismatched cutoffs (e.g., with the use of microbiologic assay cutoff with RPBA data) for risk of deficiency on the basis of megaloblastic anemia as a hematologic indicator in persons ≥4 y of age (e.g., serum folate concentration <7 nmol/L and RBC folate concentration <305 nmol/L derived with the use of a microbiologic assay), possible deficiency on the basis of rising homocysteine as a metabolic indicator in persons ≥4 y of age (e.g., serum folate concentration <10 nmol/L and RBC folate concentration <340 nmol/L derived with the use of an RPBA), and insufficiency on the basis of elevated risk of neural tube defects in women 12-49 y old (e.g., RBC folate concentration <906 nmol/L derived with the use of a microbiologic assay).

RESULTS

Pre-folic acid fortification (1988-1994), risks of deficiency for assay-matched compared with assay-mismatched cutoffs were 5.6% compared with 16% (serum folate), respectively, and 7.4% compared with 28% (RBC folate), respectively; risks declined postfortification (1999-2006) to <1% compared with <1% (serum folate), respectively, and to <1% compared with 2.5% (RBC folate), respectively. Prefortification (1988-1994), risks of possible deficiency for assay-matched compared with assay-mismatched cutoffs were 35% compared with 56% (serum folate), respectively, and 37% compared with 84% (RBC folate), respectively; risks declined postfortification (1999-2006) to 1.9% compared with 7.0% (serum folate), respectively, and to 4.8% compared with 53% (RBC folate), respectively. Postfortification (2007-2010), risks of insufficiency were 3% (assay matched) compared with 39% (assay mismatched), respectively.

CONCLUSIONS

The application of assay-mismatched cutoffs leads to a misinterpretation of folate status. This confusion likely applies to clinical assays because no comparability data are available, to our knowledge.

Lipid profiling of polarized human monocyte-derived macrophages

The highly orchestrated transcriptional and metabolic reprogramming during activation drastically transforms the main functions and physiology of human macrophages across the polarization spectrum. Lipids, for example, can modify protein function by acting remotely as signaling molecules but also locally by altering the physical properties of cellular membranes. These changes play key roles in the functions of highly plastic immune cells due to their involvement in inflammation, immune responses, phagocytosis and wound healing processes. We report an analysis of major membrane lipids of distinct phenotypes of resting (M0), classically activated (M1), alternatively activated (M2a) and deactivated (M2c) human monocyte derived macrophages from different donors. Samples were subjected to supercritical fluid chromatography-ion mobility-mass spectrometry analysis, which allowed separations based on lipid class, facilitating the profiling of their fatty acid composition. Different levels of arachidonic acid mobilization as well as other fatty acid changes were observed for different lipid classes in the distinct polarization phenotypes, suggesting the activation of highly orchestrated and specific enzymatic processes in the biosynthesis of lipid signaling molecules and cell membrane remodeling. Thromboxane A2 production appeared to be a specific marker of M1 polarization. These alterations to the global composition of lipid bi-layer membranes in the cell provide a potential methodology for the definition and determination of cellular and tissue activation states.

Differing mechanisms of surviving phagosomal stress among group B Streptococcus strains of varying genotypes

Group B Streptococcus (GBS), a leading cause of neonatal sepsis and meningitis, asymptomatically colonizes up to 30% of women and can persistently colonize even after antibiotic treatment. Previous studies have shown that GBS resides inside macrophages, but the mechanism by which it survives remains unknown. Here, we examined the ability of 4 GBS strains to survive inside macrophages and then focused on 2 strains belonging to sequence type (ST)-17 and ST-12, to examine persistence in the presence of antibiotics. A multiple stress medium was also developed using several stressors found in the phagosome to assess the ability of 30 GBS strains to withstand phagosomal stress. The ST-17 strain was more readily phagocytosed and survived intracellularly longer than the ST-12 strain, but the ST-12 strain was tolerant to ampicillin unlike the ST-17 strain. Exposure to sub-inhibitory concentrations of ampicillin and erythromycin increased the level of phagocytosis of the ST-17 strain, but had no effect on the ST-12 strain. In addition, blocking acidification of the phagosome decreased the survival of the ST-17 strain indicating a pH-dependent survival mechanism for the ST-17 strain. Congruent with the macrophage experiments, the ST-17 strain had a higher survival rate in the multiple stress medium than the ST-12 strain, and overall, serotype III isolates survived significantly better than other serotypes. These results indicate that diverse GBS strains may use differing mechanisms to persist and that serotype III strains are better able to survive specific stressors inside the phagosome relative to other serotypes.

Neither vaginal nor buccal administration of 800 μg misoprostol alters mucosal and systemic immune activation or the cervicovaginal microbiome: a pilot study

OBJECTIVES

The aim of the study was to assess the extent to which misoprostol alters mucosal or systemic immune responses following either buccal or vaginal administration.

METHODS

This was a prospective, crossover pilot study of 15 healthy, reproductive-age women. Women first received 800 μg misoprostol either via buccal or vaginal administration and were crossed over 1 month later to receive the drug via the other route. Cervicovaginal lavage samples, cervical Cytobrush samples, cervicovaginal swabs, urine and blood were obtained immediately prior to drug administration and the following day. Parameters assessed included urine and cervicovaginal misoprostol levels, whole blood cytokine responses (by ELISA) to immune stimulation with lipopolysaccharide, peripheral blood and cervical lymphocyte phenotyping by flow cytometry, cervicovaginal antimicrobial peptide measurement by ELISA and vaginal microbial ecology assessment by 16S rRNA sequencing.

RESULTS

Neither buccal nor vaginal misoprostol significantly altered local or systemic immune and microbiological parameters.

CONCLUSION

In this pilot study, we did not observe significant alteration of mucosal or systemic immunology or vaginal microbial ecology 1 day after drug administration following either the buccal or vaginal route.

Prostaglandin E2 Regulation of Macrophage Innate Immunity

Globally, maternal and fetal health is greatly impacted by extraplacental inflammation. Group B Streptococcus (GBS), a leading cause of chorioamnionitis, is thought to take advantage of the uterine environment during pregnancy in order to cause inflammation and infection. In this study, we demonstrate the metabolic changes of murine macrophages caused by GBS exposure. GBS alone prompted a delayed increase in lactate production, highlighting its ability to redirect macrophage metabolism from aerobic to anaerobic respiration. This production of lactate is thought to aid in the development and propagation of GBS throughout the surrounding tissue. Additionally, this study shows that PGE2 priming was able to exacerbate lactate production, shown by the rapid and substantial lactate increases seen upon GBS exposure. These data provide a novel model to study the role of GBS exposure to macrophages with and without PGE2 priming.

Reciprocal inhibition becomes facilitation after spinal cord injury: clinical application of a system identification approach

Alteration in spinal inputs from descending pathways following spinal cord injury (SCI) affects different mechanisms including reciprocal Ia inhibition. However, whether there is a consistent pattern of change in reciprocal inhibition following SCI is uncertain. Typical attempts to evaluate reciprocal inhibition have been restricted to electrophysiological measurements, which may have limited translation to function. Our objective was to address the uncertainty regarding changes in reciprocal inhibition after SCI by quantitatively evaluating reciprocal inhibition of ankle extensors from ankle flexors using our novel, more functionally relevant system identification approach. To evaluate reciprocal inhibition using the system identification technique, a series of small-amplitude PseudoRandom Binary Sequence (PRBS) perturbations were applied to the ankle when subjects contracted their dorsiflexors. Depression of reflex stiffness with tibialis anterior (TA) activation was evaluated as reciprocal inhibition. Our results showed that reflex stiffness decreased continuously as dorsiflexor torque increased in the healthy control subjects whereas it remained almost unchanged in the SCI subjects, indicating the absence of reciprocal inhibition in patients. This pattern was consistent with the results obtained from electrophysiological measures in a exploratory control experiment revealing depression of the control H-reflex but no change to the SCI H-reflex. These findings suggest that our system identification mechanical technique is a reliable and valid approach for evaluating reciprocal inhibition. Furthermore, our results demonstrate that reciprocal inhibition can diminish or change to reciprocal facilitation after SCI, which in turn can result in reflex hyperexcitability and unwanted activity of ankle extensors triggered by TA activity. This suggests that reciprocal facilitation may play a major role in pathophysiology of spasticity and impaired function.