Natural killer cells and innate lymphoid cells but not NKT cells are mature in their cytokine production at birth.

Early life is a time of increased susceptibility to infectious diseases and development of allergy. Innate lymphocytes are crucial components of the initiation and regulation of immune responses at mucosal surfaces, but functional differences in innate lymphocytes early in life are not fully described. We aimed to characterize the abundance and function of different innate lymphocyte cell populations in cord blood in comparison to that of adults. Blood was collected from adult donors and umbilical vessels at birth. Multicolor flow cytometry panels were used to identify and characterize lymphocyte populations and their capacity to produce hallmark cytokines. Lymphocytes were more abundant in cord blood compared to adults, however, mucosal-associated invariant T cells and natural killer T (NKT)-like cells, were far less abundant. The capacity of NKT-like cells to produce cytokines and their expression of the cytotoxic granule protein granzyme B and the marker of terminal differentiation CD57 were much lower in cord blood than in adults. In contrast, natural killer (NK) cells were as abundant in cord blood as in adults, they could produce IFNγ, and their expression of granzyme B was not significantly different from that of adult NK cells, although CD57 expression was lower. All innate lymphoid cell (ILC) subsets were more abundant in cord blood, and ILC1 and ILC2 were capable of production of IFNγ and IL-13, respectively. In conclusion, different innate lymphoid cells differ in both abundance and function in peripheral blood at birth and with important implications for immunity in early life.

HIV-Associated Alterations of the Biophysical Features of Maternal Antibodies Correlate With Their Reduced Transfer Across the Placenta.

BACKGROUND: Human immunodeficiency virus (HIV) infection during pregnancy is associated with reduced transplacental transfer of maternal antibodies and increased risk of severe infections in children who are exposed and uninfected with HIV. The basis of this reduced transfer of maternal immunity has not yet been defined but could involve modifications in the biophysical features of antibodies. The objective of this study was to assess the impact of maternal HIV infection on the biophysical features of serum IgG and transplacental antibody transfer. METHODS: Maternal serum IgG subclass levels, Fc glycosylation, Fc receptor (FcR) binding, and transplacental transfer of pathogen-specific maternal IgG were measured in pregnant women with HIV (WWH) and pregnant women testing negative for HIV (WNH) in Cape Town, South Africa. RESULTS: Maternal antibody profiles were strikingly different between pregnant WWH and WNH. Antibody binding to FcγR2a and FcγR2b, IgG1 and IgG3 antibodies, and agalactosylated antibodies were all elevated in WWH, whereas digalactosylated and sialylated antibodies were reduced compared to pregnant WNH. Antibody features that were elevated in WWH were also correlated with reduced transplacental transfer of vaccine antigen-specific antibodies. CONCLUSIONS: HIV infection is associated with marked alterations of biophysical features of maternal IgG and reduced placental transfer, potentially impairing antimicrobial immunity.

Women's views on accepting COVID-19 vaccination during and after pregnancy, and for their babies: a multi-methods study in the UK.

BACKGROUND: COVID-19 vaccines are advised for pregnant women in the United Kingdom (UK) however COVID-19 vaccine uptake among pregnant women is inadequate. METHODS: An online survey and semi-structured interviews were used to investigate pregnant women's views on COVID-19 vaccine acceptability for themselves when pregnant, not pregnant and for their babies. One thousand one hundred eighty-one women, aged over 16 years, who had been pregnant since 23rd March 2020, were surveyed between 3rd August-11th October 2020. Ten women were interviewed. RESULTS: The majority of women surveyed (81.2%) reported that they would 'definitely' or were 'leaning towards' accepting a COVID-19 vaccine when not pregnant. COVID-19 vaccine acceptance was significantly lower during pregnancy (62.1%, p < 0.005) and for their babies (69.9%, p < 0.005). Ethnic minority women were twice as likely to reject a COVID-19 vaccine for themselves when not pregnant, pregnant and for their babies compared to women from White ethnic groups (p < 0.005). Women from lower-income households, aged under 25-years, and from some geographic regions were more likely to reject a COVID-19 vaccine when not pregnant, pregnant and for their babies. Multivariate analysis revealed that income and ethnicity were the main drivers of the observed age and regional differences. Women unvaccinated against pertussis in pregnancy were over four times more likely to reject COVID-19 vaccines when not pregnant, pregnant and for their babies. Thematic analysis of the survey freetext responses and interviews found safety concerns about COVID-19 vaccines were common though wider mistrust in vaccines was also expressed. Trust in vaccines and the health system were also reasons women gave for accepting COVID-19 vaccines. CONCLUSION: Safety information on COVID-19 vaccines must be clearly communicated to pregnant women to provide reassurance and facilitate informed pregnancy vaccine decisions. Targeted interventions to promote COVID-19 vaccine uptake among ethnic minority and lower-income women may be needed.

Correction: Epstein-Barr virus nuclear antigen EBNA-LP is essential for transforming naïve B cells, and facilitates recruitment of transcription factors to the viral genome.

[This corrects the article DOI: 10.1371/journal.ppat.1006890.].

Antibody glycosylation in pregnancy and in newborns: biological roles and implications.

PURPOSE OF REVIEW: Glycosylation patterns have the potential to affect the function of antibody, antibody half-life and transplacental transfer from mother to foetus. Here, we review recent advances in our understanding of how glycosylation patterns of antibodies may be altered during pregnancy, vaccination and infection. RECENT FINDINGS: During pregnancy, there is preferential transplacental transfer of natural killer (NK) cell-activating antibodies that are galactosylated and sialylated, against both bacterial and viral antigens. Markers of NK cell function are also associated with a higher abundance of galactosylation and sialylation in respiratory syncytial virus-specific IgG, compared with total IgG, in infants up to 7 months of age which may suggest a role for NK-cell activating antibodies as important mediators of immunity during early infancy. Differential glycosylation patterns have been observed in some respiratory conditions, as increased nongalactosylated antibodies have been associated with the development of chronic inflammatory bronchopulmonary dysplasia (BPD) in preterm infants. Glycosylation patterns in children appear age-dependent, which could modulate the effector function of IgG. The clinical relevance of these findings needs to be established. SUMMARY: Glycosylation plays a key role in mediating antibody function. Glycosylation patterns associated with positive outcomes from infection in mothers and infants could inform the design of the next generation of vaccines for use in pregnancy and infancy. SDC VIDEO LINK:: http://links.lww.com/COID/A29.

Epstein-Barr virus nuclear antigen EBNA-LP is essential for transforming naïve B cells, and facilitates recruitment of transcription factors to the viral genome.

The Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) is the first viral latency-associated protein produced after EBV infection of resting B cells. Its role in B cell transformation is poorly defined, but it has been reported to enhance gene activation by the EBV protein EBNA2 in vitro. We generated EBNA-LP knockout (LPKO) EBVs containing a STOP codon within each repeat unit of internal repeat 1 (IR1). EBNA-LP-mutant EBVs established lymphoblastoid cell lines (LCLs) from adult B cells at reduced efficiency, but not from umbilical cord B cells, which died approximately two weeks after infection. Adult B cells only established EBNA-LP-null LCLs with a memory (CD27+) phenotype. Quantitative PCR analysis of virus gene expression after infection identified both an altered ratio of the EBNA genes, and a dramatic reduction in transcript levels of both EBNA2-regulated virus genes (LMP1 and LMP2) and the EBNA2-independent EBER genes in the first 2 weeks. By 30 days post infection, LPKO transcription was the same as wild-type EBV. In contrast, EBNA2-regulated cellular genes were induced efficiently by LPKO viruses. Chromatin immunoprecipitation revealed that EBNA2 and the host transcription factors EBF1 and RBPJ were delayed in their recruitment to all viral latency promoters tested, whereas these same factors were recruited efficiently to several host genes, which exhibited increased EBNA2 recruitment. We conclude that EBNA-LP does not simply co-operate with EBNA2 in activating gene transcription, but rather facilitates the recruitment of several transcription factors to the viral genome, to enable transcription of virus latency genes. Additionally, our findings suggest that EBNA-LP is essential for the survival of EBV-infected naïve B cells.

Macrophage Exosomes Induce Placental Inflammatory Cytokines: A Novel Mode of Maternal-Placental Messaging.

During pregnancy, the placenta forms the interface between mother and fetus. Highly controlled regulation of trans-placental trafficking is therefore essential for the healthy development of the growing fetus. Extracellular vesicle-mediated transfer of protein and nucleic acids from the human placenta into the maternal circulation is well documented; the possibility that this trafficking is bi-directional has not yet been explored but could affect placental function and impact on the fetus.We hypothesized that the ability of the placenta to respond to maternal inflammatory signals is mediated by the interaction of maternal immune cell exosomes with placental trophoblast. Utilizing the BeWo cell line and whole placental explants, we demonstrated that the human placenta internalizes macrophage-derived exosomes in a time- and dose-dependent manner. This uptake was via clathrin-dependent endocytosis. Furthermore, macrophage exosomes induced release of proinflammatory cytokines by the placenta. Taken together, our data demonstrates that exosomes are actively transported into the human placenta and that exosomes from activated immune cells modulate placental cytokine production. This represents a novel mechanism by which immune cells can signal to the placental unit, potentially facilitating responses to maternal inflammation and infection, and thereby preventing harm to the fetus.

In autoimmune hepatitis type 1 or the autoimmune hepatitis-sclerosing cholangitis variant defective regulatory T-cell responsiveness to IL-2 results in low IL-10 production and impaired suppression.

UNLABELLED: Defective immune regulation plays a permissive role enabling effector cells to initiate and perpetuate tissue damage, eventually resulting in autoimmune disease. Numerical and functional regulatory T-cell (Treg) impairment has been previously reported in autoimmune liver disease (AILD; including autoimmune hepatitis and autoimmune sclerosing cholangitis ASC). However, in these early reports, Tregs were phenotypically defined as CD4(+) CD25(+) or CD4(+) CD25(high) cells. In the current study, we reexamined phenotypic and functional properties of Tregs by adopting a more refined definition of these cells that also includes negativity or low level of expression of CD127. We studied 43 AILD patients and 22 healthy subjects (HSs) and found that CD4(+) CD25(+) CD127(-) Tregs were decreased in the former. This decrease was more marked in patients with active disease than in those in remission. In AILD, Treg frequencies correlated inversely with parameters of disease activity and were not affected by immunosuppressive treatment. We also document, for the first time, that, in AILD, bona-fide Tregs produce less interleukin (IL)-10 and are impaired in their ability to suppress CD4(+) CD25(-) target cell proliferation, a feature that in HSs, but not in AILDs, is dependent, at least in part, on IL-10 secretion. Decreased IL-10 production by Tregs in AILD is linked to poor responsiveness to IL-2 and phospho signal transducer and activator of transcription 5 up-regulation. CONCLUSION: Tregs are numerically impaired in AILD, this impairment being more prominent during active disease. Notably, defective IL-10 production, resulting from low Treg responsiveness to IL-2, contributes to Treg functional impairment.

Dysfunctional CD39(POS) regulatory T cells and aberrant control of T-helper type 17 cells in autoimmune hepatitis.

UNLABELLED: Autoimmune hepatitis (AIH) is an important cause of severe liver disease and is associated with both quantitative and qualitative regulatory T-cell (Treg) impairments. Tregs express CD39, an ectonucleotidase responsible for extracellular nucleotide hydrolysis, culminating in the production of immunosuppressive adenosine. Here, we describe multiple CD39(pos) Treg defects that potentially contribute to the impaired immunoregulation that is characteristic of AIH. We have examined the frequency and phenotype of CD39(pos) Tregs by flow cytometry and measured their ectonucleotidase activity. The capacity of CD4(pos) CD25(high) , CD4(pos) CD25(high) CD39(pos) , and CD4(pos) CD25(high) CD39(neg) subsets to suppress both proliferation of effector T cells and interleukin (IL)-17 production was evaluated. In AIH, CD39(pos) Tregs are decreased in frequency, exhibit limited adenosine triphosphate/adenosine diphosphate hydrolysis activity, and fail to suppress IL-17 production by effector CD4 T cells. Moreover, these CD39(pos) Tregs display a more proinflammatory profile in AIH, which is characterized by elevated CD127 positivity, and a greater propensity to produce interferon-gamma or IL-17 upon challenge with proinflammatory stimuli. CONCLUSIONS: In AIH, CD39(pos) Tregs are decreased in number, fail to adequately hydrolyze proinflammatory nucleotides and do not efficiently suppress IL-17 production by effector CD4 T cells. CD39(pos) Tregs show plasticity and are unstable upon proinflammatory challenge, suggesting that defective immunoregulation in AIH might result not only from reduced Treg number and function, but also from increased conversion of Tregs into effector cells.

Retinoic acid stabilizes antigen-specific regulatory T-cell function in autoimmune hepatitis type 2.

Imbalance between effector and regulatory T-cells (Treg) underlies the loss of immune-tolerance to self-antigens in autoimmune disease. In autoimmune hepatitis type 2 (AIH-2), effector CD4 T-cell immune responses to cytochrome P450IID6 (CYP2D6) are permitted by numerically and functionally impaired Treg. Restoration of CYP2D6-specific Treg in AIH-2 would enable control over effectors sharing the same antigen specificity, leading to re-establishment of immune-tolerance. We have previously developed a protocol for generating antigen-specific Treg through co-culture with semi-mature dendritic cells presenting CYP2D6 peptides. In this study, we aimed to explore phenotypic and functional features of patient Treg compared to health, to test Treg stability under pro-inflammatory conditions, and to investigate the potential benefit of supplementation with all-trans-retinoic acid (RA) or rapamycin (RP), agents proven to enhance Treg function. We show that antigen-specific Treg from patients have comparable phenotypic and functional features to those from healthy controls, suppressing both proliferation and pro-inflammatory cytokine production by effector cells. Treg exposure to inflammatory challenge results in decreased suppressive function and up-regulation of Th1/Th2/Th17 transcription factors both in health and AIH-2. The increase of Th1 and Th17 transcription factors is limited by addition of RA in controls and Th1 expression is decreased by RP in patients. Importantly, inflammation-induced decrease in Treg function is also abrogated by RA/RP in health and RA in patients. Our data provide important information for the optimization of protocols aiming at generating antigen-specific Treg for treatment of autoimmune disease and for understanding their biology upon pro-inflammatory challenge and RP/RA supplementation.

Inhibition of interleukin-17 promotes differentiation of CD25⁻ cells into stable T regulatory cells in patients with autoimmune hepatitis.

BACKGROUND & AIMS: Patients with autoimmune hepatitis (AIH) have reduced numbers and function of CD4+CD25(high)FOXP3+ T regulatory cells (Tregs). Tregs can be generated from CD25⁻ (ngTreg) cells, which suppress the immune response less efficiently than Tregs. We investigated whether their differentiation into T-helper (Th)17 cells, an effector subset that has the same CD4+ progenitors as Tregs, accounts for the reduced suppressive functions of ngTregs. We investigated whether blocking interleukin (IL)-17 increased the immunosuppressive activity of Tregs. METHODS: ngTregs were generated from 36 patients with AIH and 23 healthy subjects (controls). During Treg differentiation, expression of IL-17 was inhibited by physical removal of IL-17-secreting cells, exposure to recombinant transforming growth factor ß or neutralizing antibodies against IL-6 and IL-1ß (to promote differentiation of ngTregs vs Th17 cells), small inhibitory RNAs specific for the Th17 transcription factor RORC, or a combination of all these approaches. RESULTS: ngTregs from patients with AIH contained greater proportions of IL-17+ and RORC+ cells than Tregs from controls. All approaches to inhibit IL-17 increased expression of FOXP3 by ngTregs and their suppressive functions. Inhibition of IL-17 led to development of ngTregs that were phenotypically stable and did not acquire proinflammatory properties after exposure to IL-6 and IL-1ß. CONCLUSIONS: Blocking Th17 allows ngTregs to differentiate into functionally stable immune inhibitory cells; this approach might be developed for therapy of patients with AIH.

The impaired immune regulation of autoimmune hepatitis is linked to a defective galectin-9/tim-3 pathway.

UNLABELLED: In autoimmune hepatitis (AIH), liver-damaging CD4 T cell responses are associated with defective CD4(pos) CD25(pos) regulatory T cells (T-regs). Galectin-9 (Gal9), a ß-galactosidase-binding protein expressed by T-regs, is key to their function, inhibiting T helper 1 immune responses by binding T cell immunoglobulin and mucin domain 3 (Tim-3) on CD4 effector cells. We investigated whether impaired immunoregulation in AIH results from reduced expression of Gal9 in T-regs and/or Tim-3 on CD4 effector cells. Circulating Gal9(pos) CD4(pos) CD25(pos) and Tim-3(pos) CD4(pos) CD25(neg) T cell phenotype was assessed by flow cytometry in 75 AIH patients. To evaluate whether Tim-3 expression renders CD4(pos) CD25(neg) T cells amenable to T-reg control, purified CD4(pos) CD25(neg) Tim-3(pos) (Tim-3(pos)) and CD4(pos) CD25(neg) Tim-3(neg) (Tim-3(neg)) cells were cocultured with T-regs. To determine whether Gal9 expression is essential to function, T-regs were treated with small interfering RNA (siRNA) to repress Gal-9 translation; T-reg suppressor function was assessed by proliferation. In AIH, Tim-3(pos) cells within CD4(pos) CD25(neg) cells and their T-bet(pos) and RORC(pos) subsets were fewer and contained higher numbers of interferon-γ (IFNγ)(pos) and interleukin (IL)-17(pos) cells than healthy subjects (HS). In AIH and HS, Tim-3(pos) cells proliferated less vigorously and were more susceptible to T-reg control than Tim-3(neg) cells. In AIH, Gal9(pos) T-regs were fewer and contained less FOXP3(pos), IL-10(pos), and transforming growth factor ß(pos) and more IFNγ(pos) and IL-17(pos) cells than HS. siRNA treatment of Gal-9(pos) T-regs drastically reduced T-reg ability to suppress CD4(pos) CD25(neg) and Tim-3(pos) cell proliferation in AIH and HS. Tim-3(pos) cell percentage correlated inversely with aminotransferase and CD25(neg) T-bet(pos) cell values. CONCLUSION: Reduced levels of Tim-3 on CD4(pos) CD25(neg) effector cells and of Gal9 in T-regs contribute to impaired immunoregulation in AIH by rendering effector cells less prone to T-reg control and T-regs less capable of suppressing.

Circulating extracellular vesicles in healthy and pathological pregnancies: A scoping review of methodology, rigour and results.

Extracellular vesicles (EVs) play a crucial role in pregnancy, revealed by the presence of placental-derived EVs in maternal blood, their in vitro functionality, and their altered cargo in pregnancy pathologies. These EVs are thought to be involved in the development of pregnancy pathologies, such as pre-eclampsia, pre-term birth, and fetal growth restriction, and have been suggested as a source of biomarkers for gestational diseases. However, to accurately interpret their function and biomarker potential, it is necessary to critically evaluate the EV isolation and characterization methodologies used in pregnant cohorts. In this systematic scoping review, we collated the results from 152 studies that have investigated EVs in the blood of pregnant women, and provide a detailed analysis of the EV isolation and characterization methodologies used. Our findings indicate an overall increase in EV concentrations in pregnant compared to non-pregnant individuals, an increased EV count as gestation progresses, and an increased EV count in some pregnancy pathologies. We highlight the need for improved standardization of methodology, greater focus on gestational changes in EV concentrations, and further investigations into the functionality of EVs. Our review suggests that EVs hold great promise as diagnostic and translational tools for gestational diseases. However, to fully realize their potential, it is crucial to improve the standardization and reliability of EV isolation and characterization methodologies, and to gain a better understanding of their functional roles in pregnancy pathologies.

Immune cell activation by trophoblast-derived microvesicles is mediated by syncytin 1.

Envelope glycoproteins of human endogenous retrovirus (HERV), such as syncytin 1 (HERV-W), are highly expressed in the placenta and some family members have immunomodulatory properties. Placental microvesicles (MV), which are shed into the maternal circulation during pregnancy, have been demonstrated to induce immune cell activation. Therefore, the aim of this study was to investigate the immunological properties of the highly expressed placental HERV-W protein, syncytin 1, and its potential involvement in placental MV modulation of immune cell activity. The MV shed from first trimester, normal term and pre-eclamptic term placentas, and from the BeWo trophoblast cell line, all contain syncytin 1. Recombinant syncytin 1 and syncytin 1-positive BeWo trophoblast MV both induced peripheral blood mononuclear cell (PBMC) activation, indicated through production of cytokines and chemokines. Reducing syncytin 1 content in BeWo MV inhibited PBMC activation. Recombinant syncytin 1 and syncytin-1-positive BeWo MV dampened PBMC responses to lipopolysaccharide challenge. Our findings suggest that syncytin 1 is shed from the placenta into the maternal circulation in association with MV, and modulates immune cell activation and the responses of immune cells to subsequent lipopolysaccharide stimulation. These studies implicate placental MV-associated HERV in fetal regulation of the maternal immune system.

Heightened pro-inflammatory effect of preeclamptic placental microvesicles on peripheral blood immune cells in humans.

Normal pregnancy is associated with the presence of circulating placental microvesicles (MVs). Increased MV shedding and altered immune activation are seen in patients with preeclampsia, suggesting that placental MVs may play a role in the pathophysiology of this disease. Therefore, the aim of this study was to investigate the activation of peripheral blood mononuclear cells (PBMCs) by MVs shed by first-trimester, normal term, and preeclamptic term placenta. First-trimester and preeclamptic term, but not normal term, placental-derived MVs activated PBMCs, as evidenced by elevated IL1B. Significant changes were also seen with several other cytokines and chemokines, and in general when compared to normal term MVs, preeclamptic MVs induced a greater pro-inflammatory response in PBMCs. Pretreatment of PBMCs with first-trimester or normal term placental MVs resulted in a dampened IL1B response to a subsequent lipopolysaccharide (LPS) challenge. In contrast, treatment of PBMCs with preeclamptic term placental MVs exacerbated the LPS response. This was also the case for several other cytokines and chemokines. These studies suggest that placental MVs can modulate basal peripheral immune cell activation and responsiveness to LPS during normal pregnancy, and that in preeclampsia this effect is exacerbated.

Determination of Maternal and Infant Immune Responses to Pertussis Vaccination in Pregnancy.

The Bordetella pertussis bacterium is the causative agent of whooping cough (pertussis disease). Following recent outbreaks of pertussis, disproportionately affecting young infants, several countries have introduced maternal pertussis vaccination strategies, aimed at boosting transplacental transfer of protective antibodies during pregnancy. Given historical associations between high maternal antibody and blunted infant responses to vaccination, subsequent research studies have investigated the impact of maternal pertussis vaccine on infant humoral responses. However, far less is known about the potential impact of the vaccine on innate immunity. Here, we describe methods to detect in vitro cellular responses to B. pertussis in mothers and their infants using a B. pertussis stimulation assay and multiplex cytokine assays to address this research question.

Distinct non-coding RNA cargo of extracellular vesicles from M1 and M2 human primary macrophages.

Macrophages are important antigen presenting cells which can release extracellular vesicles (EVs) carrying functional cargo including non-coding RNAs. Macrophages can be broadly classified into M1 'classical' and M2 'alternatively-activated' macrophages. M1 macrophages have been linked with inflammation-associated pathologies, whereas a switch towards an M2 phenotype indicates resolution of inflammation and tissue regeneration. Here, we provide the first comprehensive analysis of the small RNA cargo of EVs from human M1 and M2 primary macrophages. Using small RNA sequencing, we identified several types of small non-coding RNAs in M1 and M2 macrophage EVs including miRNAs, isomiRs, tRNA fragments, piRNA, snRNA, snoRNA and Y-RNA fragments. Distinct differences were observed between M1 and M2 EVs, with higher relative abundance of miRNAs, and lower abundance of tRNA fragments in M1 compared to M2 EVs. MicroRNA-target enrichment analysis identified several gene targets involved in gene expression and inflammatory signalling pathways. EVs were also enriched in tRNA fragments, primarily originating from the 5' end or the internal region of the full length tRNAs, many of which were differentially abundant in M1 and M2 EVs. Similarly, several other small non-coding RNAs, namely snRNAs, snoRNAs and Y-RNA fragments, were differentially enriched in M1 and M2 EVs; we discuss their putative roles in macrophage EVs. In conclusion, we show that M1 and M2 macrophages release EVs with distinct RNA cargo, which has the potential to contribute to the unique effect of these cell subsets on their microenvironment.

Watermelon-Derived Extracellular Vesicles Influence Human Ex Vivo Placental Cell Behavior by Altering Intestinal Secretions.

SCOPE: During pregnancy, mother-to-fetus transfer of nutrients is mediated by the placenta; sub-optimal placental development and/or function results in fetal growth restriction (FGR), and the attendant risk of stillbirth, neurodevelopmental delay, and non-communicable diseases in adulthood. A maternal diet high in fruit and vegetables lowers the risk of FGR but the association cannot be explained fully by known macro- and micronutrients. METHODS AND RESULTS: This study investigates if dietary-derived extracellular vesicles (EVs) can regulate placental function. The study characterizes the microRNA and protein cargo of EVs isolated from watermelon, show they are actively internalized by human intestinal epithelial cells in vitro, use mass spectrometry to demonstrate that they alter the intestinal secretome and bioinformatic analyses to predict the likely affected pathways in cells/tissues distal to gut. Application of the watermelon EV-modified intestinal secretome to human placental trophoblast cells and ex vivo tissue explants affects the trophoblast proteome and key aspects of trophoblast behavior, including migration and syncytialization. CONCLUSION: Dietary-derived plant EVs can modify intestinal communication with distal tissues, including the placenta. Harnessing the beneficial properties of dietary-derived plant EVs and/or exploiting their potential as natural delivery agents may provide new ways to improve placental function and reduce rates of FGR.

Women's views and experiences of accessing pertussis vaccination in pregnancy and infant vaccinations during the COVID-19 pandemic: A multi-methods study in the UK.

BACKGROUND: COVID-19 changed access to healthcare, including vaccinations, in the United Kingdom (UK). This study explored UK women's experiences of accessing pertussis vaccination during pregnancy and infant vaccinations during COVID-19. METHODS: An online cross-sectional survey was completed, between 3rd August-11th October 2020, by 1404 women aged 16+ years who were pregnant at some point after the first UK lockdown from March 23rd, 2020. Ten follow-up semi-structured interviews were conducted. RESULTS: Most women surveyed were pregnant (65.7%) and a third postnatal (34.3%). Almost all women (95.6%) were aware that pertussis vaccination is recommended in pregnancy. Most pregnant (72.1%) and postnatal women (84.0%) had received pertussis vaccination; however, access issues were reported. Over a third (39.6%) of women had a pregnancy vaccination appointment changed. COVID-19 made it physically difficult to access pregnancy vaccinations for one fifth (21.5%) of women and physically difficult to access infant vaccinations for almost half of women (45.8%). Nearly half of women (45.2%) reported feeling less safe attending pregnancy vaccinations and over three quarters (76.3%) less safe attending infant vaccinations due to COVID-19. The majority (94.2%) felt it was important to get their baby vaccinated during COVID-19. Pregnant women from ethnic-minorities and lower-income households were less likely to have been vaccinated. Minority-ethnicity women were more likely to report access problems and feeling less safe attending vaccinations for both themselves and their babies. Qualitative analysis found women experienced difficulties accessing antenatal care and relied on knowledge from previous pregnancies to access vaccines in pregnancy. CONCLUSION: During the ongoing and future pandemics, healthcare services should prioritise equitable access to routine vaccinations, including tailoring services for ethnic-minority families who experience greater barriers to vaccination.

Placental macrophage responses to viral and bacterial ligands and the influence of fetal sex.

Bacterial and viral infections of the placenta are associated with inflammation and adverse pregnancy outcomes. Hofbauer cells (HBCs) are fetal-origin macrophages in the placenta, proposed to protect the fetus from vertical pathogen transmission. We performed quantitative proteomics on term HBCs under resting conditions and following exposure to bacterial and viral pathogen-associated molecular patterns (PAMPs), and investigated the contribution of fetal sex. Resting HBCs expressed proteins pertinent to macrophage function, including chemokines, cytokines, Toll-like receptors, and major histocompatibility complex class I and II molecules. HBCs mounted divergent responses to bacterial versus viral PAMPs but exhibited protein expression changes suggestive of a more pro-inflammatory phenotype. A comparison between male and female HBCs showed that the latter mounted a stronger and wider response. Here, we provide a comprehensive understanding of the sex-dependent responses of placental macrophages to infectious triggers, which were primarily associated with lipid metabolism in males and cytoskeleton organization in females.