Oropouche virus (OROV) is an emerging orthobunyavirus responsible for widespread outbreaks across South and Central America. The recent surge in congenital infections has raised urgent concerns about OROV's threat to maternal and fetal health. Here, we establish an in vivo model of OROV vertical transmission using the ancestral (prototype) strain BeAn19991 in immunocompetent C57BL/6J mice. We demonstrate that OROV efficiently replicates in maternal tissues, crosses the maternal-fetal interface, and infects both placental and fetal tissues. Parallel infections in human trophoblast-derived cell lines confirm conserved placental tropism across the ancestral strain and a contemporary (outbreak) isolate from the current outbreak. Importantly, we show that vertical transmission is not a recently acquired trait but a long-standing feature of OROV biology. Offspring born to infected dams mount neutralizing antibody responses and exhibit partial protection upon challenge. These findings conclusively confirm OROV as a vertically transmissible arbovirus, highlighting the urgent need to integrate OROV into surveillance, diagnostic, and vaccine preparedness efforts.

Group B Streptococcus (GBS) is an important bacterial pathogen during pregnancy, colonizing up to 35% of pregnant people recto-vaginally. Intrauterine GBS infection during pregnancy can cause preterm labor, early membrane rupture, and, if the fetus gets infected, stillbirth or early-onset disease (EOD) following birth. Intrapartum antibiotics are recommended to treat GBS-colonized pregnant patients during labor to prevent these outcomes, particularly EOD. However, persistent GBS colonization has been observed despite antibiotic treatment. One strategy employed by bacteria to promote survival and antibiotic tolerance is the production of membrane vesicles (MVs). To understand how GBS MVs are affected by antibiotics and influence bacterial survival, we exposed a clinical GBS strain recovered from a pregnant patient with persistent colonization to antibiotics and examined the impact on MV production and composition. Using nanoparticle tracking analysis, microscopy, and proteomics, antibiotic treatment of GBS was found to significantly increase the production of MVs relative to untreated GBS (control) regardless of the antibiotic class (ampicillin; P = 4.2 × 10-6, erythromycin; P = 0.01). Moreover, antibiotic exposure yielded MVs with different protein composition compared to the untreated control, with 21 and 19 proteins unique to the ampicillin- and erythromycin-treated GBS, respectively. Increased abundance of antibiotic-specific protein targets was observed in the respective antibiotic-treated MVs, suggesting a mechanism for evading antibiotic-mediated killing. Together, these data suggest that antibiotic treatment alters both the production and composition of MVs, which can promote GBS survival in such conditions.IMPORTANCEGBS colonization during pregnancy can lead to invasive disease in neonates. Although antibiotics are given to GBS-positive pregnant patients during labor, some of these individuals remain colonized with GBS after treatment. Persistent GBS colonization is a public health concern, threatening the effectiveness of antibiotics and increasing the risk of GBS disease, especially for subsequent pregnancies. Although mechanisms linked to persistent colonization and antibiotic tolerance are poorly understood in GBS, MV production has been shown to promote bacterial survival in other species with and without antibiotic exposure. Herein, we demonstrated that two different antibiotics trigger changes in the production and composition of MVs in a persistent GBS colonizing strain, providing insight into the mechanisms used by GBS to rebound following antibiotic prophylaxis. Knowledge gained from this study can guide efforts in the development of more targeted and effective treatments for GBS disease.

Group B Streptococcus (GBS) is a major cause of fetal and neonatal mortality worldwide. Many of the adverse effects of invasive GBS are associated with inflammation; therefore, understanding bacterial factors that promote inflammation is of critical importance. Membrane vesicles (MVs), which are produced by many bacteria, may modulate host inflammatory responses. While it is known that mice injected intra-amniotically with GBS MVs exhibit large-scale leukocyte infiltration, preterm birth, and subsequent fetal death, the immune effectors driving this response remain unclear. Here, we hypothesized that THP-1 macrophage-like cells respond to GBS-derived MVs by producing proinflammatory cytokines and are recognized through one or more pattern recognition receptors. We show that THP-1s produce high levels of neutrophil- and monocyte-specific chemokines in response to MVs derived from different clinical isolates of GBS. Using antibody microarrays and multiplex Luminex assays, we found that GBS MVs elicit significantly (p < 0.05) higher levels of CCL1, CCL2, CCL20, CXCL1, CXCL10, and IL-1β relative to untreated THP-1s. Using chemical inhibitors in combination with caspase-1 activity assays and Luminex assays, we further demonstrate that GBS MVs upregulated IL-1β production in a caspase-1 and NLRP3-dependent manner, ultimately identifying NLRP3 as a sensor of GBS MVs. These data indicate that MVs contain one or more pathogen-associated molecular patterns that can be sensed by the immune system and show that the NLRP3 inflammasome is a novel sensor of GBS MVs. Our data additionally indicate that MVs may serve as immune effectors that can be targeted for immunotherapeutics.

Cesarean section is the most common surgical procedure performed worldwide. It is associated with good perinatal and maternal outcomes when indicated. The rising global cesarean birth rate has coincided with an increase in post-cesarean sepsis - specifically site infections, which have an incidence of 7% worldwide. Post-cesarean sepsis remains a serious complication that prolongs hospital stays, resulting in additional surgery and worsening maternal morbidity and mortality, and increasing healthcare costs with socioeconomic consequences. There is no global practice guide for post-cesarean sepsis, despite most maternal deaths due to sepsis occurring postpartum. Here we introduce a FIGO Committee on Infections During Pregnancy guide on prevention and treatment of post-cesarean sepsis. We encourage strategies to keep cesarean birth rates at evidence-based levels by aiming to standardize the management of labor and to increase the percentage of vaginal births after a previous cesarean. Identification of risk factors before and during the surgery is the primary step towards prevention. These measures, combined with evidence-based strategies to promote infection prevention practices, including routine prophylactic antibiotics, skin and vaginal preparation before cesarean birth, and glove change prior to skin closure, contribute towards reducing maternal morbidity and mortality.

Skin infections caused by methicillin-resistant Staphylococcus aureus present significant complications for individuals with obesity. However, the factors driving the dysregulated skin host defense and injury in these individuals remain unclear. In this study, we investigated a dysregulated molecular checkpoint, prostaglandin E2, which fails to prevent the inflammatory response from damaging infected skin during obesity, resulting in poor bacterial clearance and larger lesions. Our data show that mice with obesity cannot control S aureus skin infections, as evidenced by larger lesions, abscesses, and increased bacterial load. The heightened susceptibility to infection in mice with obesity is linked to decreased production of prostaglandin E2, lower levels of CXC chemokines, and reduced recruitment of CXCR2+ phagocytes to the infected skin. Through epistatic and gain-of-function approaches, our data demonstrate that restoring prostaglandin E2 levels with the Food and Drug Administration-approved prostaglandin E analog misoprostol reduces tissue injury and enhances bacterial clearance, acting through E-prostanoid 3-mediated cAMP inhibition that reinstates the CXC-family/ CXCR2 axis in infected mice with obesity. By uncovering both the therapeutic effects and the cellular mechanisms through which the prostaglandin E2/EP3 axis regulates the harmful inflammatory response, we advance the field, emphasizing its role in decreasing lesion size and improving host defense in pre-existing conditions.

SUMMARY Bacterial infections with Group B Streptococcus (GBS) are an important cause of adverse outcomes in pregnant individuals, neonates, and infants. GBS is a common commensal in the genitourinary and gastrointestinal tracts and can be detected in the vagina of approximately 20% of women globally. GBS can infect the fetus either during pregnancy or vaginal delivery resulting in preterm birth, stillbirth, or early-onset neonatal disease (EOD) in the first week of life. The mother can also become infected with GBS leading to postpartum endometritis, and rarely, maternal sepsis. An invasive GBS infection of the neonate may present after the first week of life (late-onset disease, LOD) through transmission from caregivers, breast milk, and other sources. Invasive GBS infections in neonates can result in sepsis, pneumonia, meningitis, neurodevelopmental impairment, death, and lifelong disability. A policy of routine screening for GBS rectovaginal colonization in well-resourced countries can trigger the administration of intrapartum antibiotic prophylaxis (IAP) when prenatal testing is positive, which drastically reduces rates of EOD. However, many countries do not routinely screen pregnant women for GBS colonization but may administer IAP in cases with a high risk of EOD. IAP does not reduce rates of LOD. A global vaccination campaign is needed to reduce the significant burden of invasive GBS disease that remains among infants and pregnant individuals. In this narrative review, we provide a comprehensive overview of the global impact of GBS colonization and infection, virulence factors and pathogenesis, and current and future prophylactics and therapeutics.

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.

BACKGROUNDS:Infection during pregnancy is a significant public health concern due to the increased risk of adverse birth outcomes. Group B Streptococcus or Streptococcus agalactiae (GBS) stands out as a major bacterial cause of neonatal morbidity and mortality. We aimed to explore the involvement of reactive oxygen species (ROS) and oxidative stress pathways in pro-inflammatory responses within human fetal membrane tissue, the target tissue of acute bacterial chorioamnionitis. METHODS:We reanalyzed transcriptomic data from fetal membrane explants inoculated with GBS to assess the impact of GBS on oxidative stress and ROS genes/pathways. We conducted pathway enrichment analysis of transcriptomic data using the Database for Annotation, Visualization and Integrated Discovery (DAVID), a web-based functional annotation/pathway enrichment tool. Subsequently, we conducted ex vivo experiments to test the hypothesis that antioxidant treatment could inhibit pathogen-stimulated inflammatory responses in fetal membranes. RESULTS:Using DAVID analysis, we found significant enrichment of pathways related to oxidative stress or ROS in GBS-inoculated human fetal membranes, for example, "Response to Oxidative Stress" (FDR = 0.02) and "Positive Regulation of Reactive Oxygen Species Metabolic Process" (FDR = 2.6*10-4 ). There were 31 significantly changed genes associated with these pathways, most of which were upregulated after GBS inoculation. In ex vivo experiments with choriodecidual membrane explants, our study showed that co-treatment with N-acetylcysteine (NAC) effectively suppressed the release of pro-inflammatory cytokines (IL-6, IL-8, TNF-α) and prostaglandin PGE2, compared to GBS-treated explants (p < .05 compared to GBS-treated samples without NAC co-treatment). Furthermore, NAC treatment inhibited the release of cytokines and PGE2 stimulated by lipoteichoic acid (LTA) and lipopolysaccharide (LPS) in whole membrane explants (p < .05 compared to LTA or LPS-treated samples without NAC co-treatment). CONCLUSIONS:Our study sheds light on the potential roles of ROS in governing the innate immune response to GBS infection, offering insights for developing strategies to mitigate GBS-related adverse outcomes.

IntroductionRupture 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.ResultsPalmitate 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.DiscussionThese 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.

Immunization strategies are part of routine pregnancy care to prevent infectious diseases in the mother, the fetus, and the newborn. Maternal immunization recommendations followed the recognition of the consequences of infectious diseases in pregnancy, including vertical transmission and perinatal consequences. The recent COVID-19 pandemic highlighted the issue of vaccination among pregnant individuals. Recommendations vary globally; however, Tdap, influenza, and, recently, COVID-19 vaccines are routinely recommended during pregnancy. There are several new maternal immunization products in the pipeline, including those directed against malaria, cytomegalovirus, Group B Streptococcus, herpes simplex virus, and respiratory syncytial virus. Important challenges must be addressed in all countries to guarantee that pregnant individuals and their babies receive the best care possible, including uptake of recommended immunizations by their entire target population groups. These challenges include disseminating appropriate data for vaccine recommendations and many others, such as ensuring stakeholder endorsement, achieving in-country distribution and administration, adequate vaccine supply, and a well-organized healthcare system, ideally offering the immunization free of charge. More recently, the hesitancy of pregnant women to receive immunizations highlights the relevance of cultural aspects and other contextual factors affecting vaccine uptake among pregnant individuals.

Group B Streptococcus (GBS) is a pathobiont that can ascend to the placenta and cause adverse pregnancy outcomes, in part through production of the toxin β‐hemolysin/cytolysin (β‐h/c). Innate immune cells have been implicated in the response to GBS infection, but the impact of β‐h/c on their response is poorly defined. We show that GBS modulates innate immune cell states by subversion of host inflammation through β‐h/c, allowing worse outcomes. We used an ascending mouse model of GBS infection to measure placental cell state changes over time following infection with a β‐h/c‐deficient and isogenic wild type GBS strain. Transcriptomic analysis suggests that β‐h/c‐producing GBS elicit a worse phenotype through suppression of host inflammatory signaling in placental macrophages and neutrophils, and comparison of human placental macrophages infected with the same strains recapitulates these results. Our findings have implications for identification of new targets in GBS disease to support host defense against pathogenic challenge.

Clostridioides difficile damages the colonic mucosa through the action of two potent exotoxins. Factors shaping C. difficile pathogenesis are incompletely understood but are likely due to the ecological factors in the gastrointestinal ecosystem, mucosal immune responses, and environmental factors. Little is known about the role of pharmaceutical drugs during C. difficile infection (CDI), but recent studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) worsen CDI. The mechanism underlying this phenomenon remains unclear. Here, we show that NSAIDs exacerbate CDI by disrupting colonic epithelial cells (CECs) and sensitizing cells to C. difficile toxin–mediated damage independent of their canonical role of inhibiting cyclooxygenase (COX) enzymes. Notably, we find that NSAIDs and C. difficile toxins target the mitochondria of CECs and enhance C. difficile toxin–mediated damage. Our results demonstrate that NSAIDs exacerbate CDI by synergizing with C. difficile toxins to damage host cell mitochondria. Together, this work highlights a role for NSAIDs in exacerbating microbial infection in the colon.

The placenta is critical to human growth and development and has been implicated in health outcomes. Understanding the mechanisms through which the placenta influences perinatal and later-life outcomes requires further investigation. We evaluated the relationships between birthweight and adult body mass index (BMI) and genetically-predicted gene expression in human placenta. Birthweight genome-wide association summary statistics were obtained from the Early Growth Genetics Consortium (N = 298,142). Adult BMI summary statistics were obtained from the GIANT consortium (N = 681,275). We used S-PrediXcan to evaluate associations between the outcomes and predicted gene expression in placental tissue and, to identify genes where placental expression was exclusively associated with the outcomes, compared to 48 other tissues (GTEx v7). We identified 24 genes where predicted placental expression was significantly associated with birthweight, 15 of which were not associated with birthweight in any other tissue. One of these genes has been previously linked to birthweight. Analyses identified 182 genes where placental expression was associated with adult BMI, 110 were not associated with BMI in any other tissue. Eleven genes that had placental gene expression levels exclusively associated with BMI have been previously associated with BMI. Expression of a single gene, PAX4 , was associated with both outcomes exclusively in the placenta. Inter-individual variation of gene expression in placental tissue may contribute to observed variation in birthweight and adult BMI, supporting developmental origins hypothesis.

We analyzed our challenging experience with a randomized controlled trial of misoprostol for prevention of recurrent C. difficile. Despite careful prescreening and thoughtful protocol modifications to facilitate enrollment, we closed the study early after enrolling just 7 participants over 3 years. We share lessons learned, noting the importance of feasibility studies, inclusion of biomarker outcomes, and dissemination of such findings to inform future research design and implementation successes.

Background In utero exposure to human immunodeficiency virus (HIV) and antiretroviral (ART) is associated with adverse birth outcomes, which are often attributed to alterations in placental morphology. This study used structural equation models (SEMs) to examine the impact of HIV and ART exposure on fetal growth outcomes and whether these associations are mediated by placental morphology in urban-dwelling Black South African women. Methods This prospective cohort study included pregnant women living with HIV (WLWH, n = 122) and not living with HIV (WNLWH, n = 250) that underwent repeated ultrasonography during pregnancy, and at delivery, to determine fetal growth parameters in Soweto, South Africa. The size and the velocity of fetal growth measures (i.e., head and abdominal circumference, biparietal diameter, and femur length) were calculated using the Superimposition by Translation and Rotation. Placenta digital photographs taken at delivery were used to estimate morphometric parameters and trimmed placental weight was measured. All WLWH were receiving ART for the prevention of vertical transmission of HIV. Results A trend towards a lower placental weight and significantly shorter umbilical cord length was reported in WLWH compared to their counterparts. After sex stratification, umbilical cord length was significantly shorter in males born to WLWH than in male fetuses born to WNLWH (27.3 (21.6–32.8) vs. 31.4 (25.0–37.0) cm, p = 0.015). In contrast, female fetuses born to WLWH had lower placental weight, birth weight (2.9 (2.3–3.1) vs. 3.0 (2.7–3.2) kg), and head circumference (33 (32–34) vs. 34 (33–35) cm) than their counterparts (all p ≤ 0.05). The SEM models showed an inverse association between HIV and head circumference size and velocity in female fetuses. In contrast, HIV and ART exposure was positively associated with femur length growth (both size and velocity) and abdominal circumference velocity in male fetuses. None of these associations appeared to be mediated via placental morphology. Conclusion Our findings suggest that HIV and ART exposure directly affects head circumference growth in females and abdominal circumference velocity in male fetuses; but may improve femur length growth in male fetuses only.

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-tetrachloro-dibenzo-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 phago-cytosis and cytokine production. Taken together, these results indicate that TCDD paralyzes placental macrophage responses to bacterial infection.