Mucosal immunity: integration between mother and the breast-fed infant

Lactose in human milk is associated with lower rates of infection during a drought

BACKGROUND

Infants given mothers' milk have higher resistance against infections than formula-fed counterparts. This protection is likely multifactorial, with roles for both milk immune factors and nutrients, particularly under elevated nutritional and disease stress.

AIM

This study evaluated several milk nutrients/immune factors to assess associations with infant infectious disease during a severe drought.

SUBJECTS AND METHODS

The study analysed morbidity recall data from Kenyan mother-infant dyads surveyed during a historic drought (n 84). Predictors of interest in logistic regression models of infant infections included milk sIgA, lactoferrin, retinol, folate receptor-α, fat, protein, and lactose. Adjustment variables included dyadic demographic characteristics and maternal infection. Akaike Information Criterion guided model fit assessment. Interactions between variables were allowed in the best-fit model.

RESULTS

In the best-fit model, lactose was inversely (OR 0.93; 90% CI 0.89, 0.97), and maternal infection was positively (OR 2.80; 90% CI 1.04, 7.52) associated with infant infection. Milk immune factors (sIgA, lactoferrin) were not included in the final models.

CONCLUSION

Mothers' milk may protect infants against infection through a broad range of immune and nutrient components. In the context of severe drought with heightened nutritional and disease stress, lactose may protect against infection or decrease in the presence of an infection.

Antibodies in breast milk: Pro-bodies designed for healthy newborn development

This manuscript sheds light on the impact of maternal breast milk antibodies on infant health. Milk antibodies prepare and protect the newborn against environmental exposure, guide and regulate the offspring's immune system, and promote transgenerational adaptation of the immune system to its environment. While the transfer of IgG across the placenta ceases at birth, milk antibodies are continuously replenished by the maternal immune system. They reflect the mother's real-time adaptation to the environment to which the infant is exposed. They cover the infant's upper respiratory and digestive mucosa and are perfectly positioned to control responses to environmental antigens and might also reach their circulation. Maternal antibodies in breast milk play a key role in the immune defense of the developing child, with a major impact on infectious disease susceptibility in both HIC and LMIC. They also influence the development of another major health burden in children-allergies. Finally, emerging evidence shows that milk antibodies also actively shape immune development. Much of this is likely to be mediated by their effect on the seeding, composition and function of the microbiota, but not only. Further understanding of the bridge that maternal antibodies provide between the child and its environment should enable the best interventions to promote healthy development.

The Role of Breastfeeding in Acute Respiratory Infections in Infancy

BACKGROUND

Acute respiratory infections (ARIs) affect the respiratory tract, are often caused by viruses such as respiratory syncytial virus and rhinovirus, and present symptoms such as coughing, fever, respiratory distress, and breathing difficulty. The global adherence to exclusive breastfeeding (BF) for the first 6 months of life has reached 44%, supported by the World Health Organization and United Nations International Children's Emergency Fund efforts. BF provides vital nutrients and contributes to infant immune system development, protecting against infections. The role of BF in preventing and reducing complications of ARIs in infants is gaining attention, prompting a review of current data and future research needs. This review aims to summarize the evidence on the role of BF in reducing the risk and severity of ARIs in infants, elucidate the adaptations in breast milk composition during infections, and identify relevant research needs.

METHODS AND RESULTS

Human milk (HM) is rich in immunoglobulins, antimicrobial peptides, and immunomodulatory factors that protect against various pathogens, including respiratory viruses. Several studies have demonstrated that BF is associated with a significant reduction in hospitalization, oxygen requirements, and mortality in infants with ARIs. The effectiveness of BF varies according to the specific respiratory virus, and a longer duration of exclusive BF appears to enhance its protective effect. It is documented that the composition of HM adjusts dynamically in response to infections, fortifying the infant's immune defenses. Specific immunological components of HM, including leukocytes and immunoglobulins, increase in response to infection in the infant, contributing to the enhancement of the immune defense in infants. Immune-boosting microRNAs enhance immune transfer to the infants and promote early gut maturation, and the HM microbiome along with other factors modifies the infant's gut microbiome and immune system.

CONCLUSIONS

BF defends infants from respiratory infections, and the investigation of the microRNAs in HM offers new insights into its antiviral properties. The promotion of BF, especially in vulnerable communities, is of paramount importance in alleviating the global burden of ARIs in infancy.

Relationship between infant gastrointestinal microorganisms and maternal microbiome within 6 months of delivery

To investigate the association between the microbiota in mothers and gut microbiota in infants from 0 to 6 months, the microbiotas in infant feces, maternal feces, and breast milk were determined by 16S rRNA gene sequencing. The contribution of each maternal microbiome to the infant was assessed using fast expectation-maximization for microbial source tracking calculations. The levels of short-chain fatty acids (SCFAs) and secretory immunoglobulin A (sIgA) in the feces of infants were also determined using gas chromatography and IDK-sIgA ELISA to gain a more comprehensive understanding of the infant gut microbiome. The results of this study showed that in addition to Firmicutes (E1) and Bifidobacterium (E2), the dominant microorganisms of the intestinal microbiota of infants aged 0-6 months include Proteobacteria, which is different from previous findings. Acetic acid, the most abundant SCFA in the infant gut, was positively correlated with Megasphaera (P < 0.01), whereas sIgA was positively correlated with Bacteroides (P < 0.05) and negatively correlated with Klebsiella and Clostridium_XVIII (P < 0.05). The maternal gut microbiota contributed more to the infant gut microbiota (43.58% ± 11.13%) than the breast milk microbiota, and significant differences were observed in the contribution of the maternal microbiota to the infant gut microbiota based on the delivery mode and feeding practices. In summary, we emphasize the key role of maternal gut health in the establishment and succession of infant gut microbiota.IMPORTANCEThis study aims to delineate the microbial connections between mothers and infants, leveraging the fast expectation-maximization for microbial source tracking methodology to quantify the contribution of maternal microbiota to the constitution of the infant's gut microbiome. Concurrently, it examines the correlations between the infant gut microbiota and two distinctive biomolecules, namely short-chain fatty acids (SCFAs) and secretory immunoglobulin A (sIgA). The findings indicate that the maternal gut microbiota exerts a greater influence on the infant's gut microbial composition than does the microbiota present in breast milk. Infants born via vaginal delivery and receiving mixed feeding display gut microbiota profiles more similar to their mothers'. Notably, the SCFA acetate displays positive associations with beneficial bacteria and inverse relationships with potentially harmful ones within the infant's gut. Meanwhile, sIgA positively correlates with Bacteroides species and negatively with potentially pathogenic bacteria. By delving into the transmission dynamics of maternal-infant microbiota, exploring the impacts of metabolic byproducts within the infant's gut, and scrutinizing how contextual factors such as birthing method and feeding practices affect the correlation between maternal and infant microbiota, this research endeavors to establish practical strategies for optimizing early-life gut health management in infants. Such insights promise to inform targeted interventions that foster healthier microbial development during the critical first 6 months of life.

Chronic exposure to polystyrene nanoplastics induces intestinal mechanical and immune barrier dysfunction in mice

Micro(nano)plastics are prevalent in the environment, and prolonged exposure to them represents a threat to human health. The goal of this study is to assess the health risk of long-term exposure to nanoplastics (NPs) at environmental concentrations on the intestinal mechanical and immune barrier in mice. In this study, mice were provided drinking water containing polystyrene NPs (PS-NPs; 0.1, 1, and 10 mg·L-1) for 32 consecutive weeks. The levels of endocytosis proteins caveolin and clathrin and of tight junctional proteins claudin-1, occludin, and ZO-1, and morphological changes, proportion of lymphocytes B in MLNs and lymphocytes T in IELs and LPLs were determined by immunohistochemistry, hematoxylin-eosin, and flow cytometry assays in the intestinal tissues of mice at 28 weeks. The activities or concentrations of ROS, SOD, MDA, and GSH-Px and inflammatory factors (IL-1β, IL-6, and TNF-α) in the intestinal tissues of mice were measured by ELISA at 12, 16, 20, 24, and 32 weeks. Compared with the control group, oral ingested PS-NPs entered the intestinal tissues of mice and upregulated expression levels of the clathrin and caveolin. The intestinal tissue structure of mice in the PS-NPs (1 and 10 mg·L-1) exposure groups showed significant abnormalities, such as villus erosion, decreased of crypts numbers and large infiltration of inflammatory cells. Exposure to 0.1 mg·L-1 PS-NPs decreased occludin protein levels, but not claudin-1 and ZO-1 levels. The levels of these three tight junction proteins decreased significantly in the 1 and 10 mg·L-1 PS-NPs exposed groups. Exposure to PS-NPs led to a significant time- and dose-dependent increase in ROS and MDA levels, and concurrently decreased GSH-Px and SOD contents. Exposure to PS-NPs increased the proportion of B cells in MLNs, and decreased the proportion of CD8+ T cells in IELs and LPLs. The levels of pro-inflammatory cytokines IL-6, TNF-α and IL-1β were markedly elevated after PS-NPs exposure. Long-term PS-NPs exposure impaired intestinal mechanical and immune barrier, and indicate a potentially significant threat to human health.

Dietary Galactose Increases the Expression of Mitochondrial OXPHOS Genes and Modulates the Carbohydrate Oxidation Pathways in Mouse Intestinal Mucosa

BACKGROUND

Prolonged lactation provides substantial health benefits, possibly because of galactose as part of milk sugar lactose. Isocaloric replacement of dietary glucose [16 energy%(en%)] with galactose within a normal diet (64en% carbohydrates) during a 3-wk postweaning period provided substantial benefits on short- and long-term physiologic and metabolic parameters at the whole-body level and liver in female mice, which might be attributable to intestinal function.

OBJECTIVES

This study aimed to investigate if partial dietary replacement of glucose with galactose alters intestinal metabolism underlying hepatic health effects.

METHODS

Proximal intestinal mucosa gene profiles in female mice were analyzed using RNAseq technology, validated, and correlated with hepatic health parameters.

RESULTS

Transcriptome analysis revealed that the presence of galactose primarily affected the pathways involved in energy metabolism. A consistently higher expression was observed in the subset of mitochondrial transcripts (78 of 80, all P.adj < 0.1). Oxidative phosphorylation (OXPHOS) represented the most upregulated process (all top 10 pathways) independent of the total mitochondrial mass (P = 0.75). Moreover, galactose consistently upregulated carbohydrate metabolism pathways, specifically glycolysis till acetyl-CoA production and fructose metabolism. Also, the expression of transcripts involved in these pathways was negatively correlated with circulating serum amyloid A3 protein, a marker of hepatic inflammation [R (-0.61, -0.5), P (0.002, 0.01)]. Accordingly, CD163+ cells were decreased in the liver. Additionally, the expression of key fructolytic enzymes in the small intestinal mucosa was negatively correlated with triglyceride accumulation in the liver [R (-0.45, -0.4), P (0.03, 0.05)].

CONCLUSIONS

To our knowledge, our results show for the first time the role of galactose as an OXPHOS activator in vivo. Moreover, the concept of intestinal cells acting as the body's metabolic gatekeeper is strongly supported, as they alter substrate availability and thereby contribute to the maintenance of metabolic homeostasis, protecting other organs, as evidenced by their potential ability to shield the liver from the potentially detrimental effects of fructose.

Human milk immune factors, maternal nutritional status, and infant sex: The INSPIRE study

OBJECTIVES

Breastfeeding is an energetically costly and intense form of human parental investment, providing sole-source nutrition in early infancy and bioactive components, including immune factors. Given the energetic cost of lactation, milk factors may be subject to tradeoffs, and variation in concentrations have been explored utilizing the Trivers-Willard hypothesis. As human milk immune factors are critical to developing immune system and protect infants against pathogens, we tested whether concentrations of milk immune factors (IgA, IgM, IgG, EGF, TGFβ2, and IL-10) vary in response to infant sex and maternal condition (proxied by maternal diet diversity [DD] and body mass index [BMI]) as posited in the Trivers-Willard hypothesis and consider the application of the hypothesis to milk composition.

METHODS

We analyzed concentrations of immune factors in 358 milk samples collected from women residing in 10 international sites using linear mixed-effects models to test for an interaction between maternal condition, including population as a random effect and infant age and maternal age as fixed effects.

RESULTS

IgG concentrations were significantly lower in milk produced by women consuming diets with low diversity with male infants than those with female infants. No other significant associations were identified.

CONCLUSIONS

IgG concentrations were related to infant sex and maternal diet diversity, providing minimal support for the hypothesis. Given the lack of associations across other select immune factors, results suggest that the Trivers-Willard hypothesis may not be broadly applied to human milk immune factors as a measure of maternal investment, which are likely buffered against perturbations in maternal condition.

Comparative Analysis of Protein Digestion Characteristics in Human, Cow, Goat, Sheep, Mare, and Camel Milk under Simulated Infant Condition

An infant in vitro digestion model was utilized to investigate protein digestion characteristics in human and diverse mammalian milk (i.e., cow, goat, sheep, mare, and camel milk) using electrophoresis and chromatography. Digestive differences among milks were mainly manifested in the infant gastric phase, as evidenced by varying degrees of protein digestion. Notably, proteins (i.e., lactoferrin, serum albumin, and immunoglobulin G-heavy chain) remained partially intact in human milk, whereas these proteins in animal milk were exclusively degraded after gastrointestinal digestion. The peptide spectra of human, mare, and camel milk were highly similar, with a predominant formation of low-intensity small peptides, whereas the other three milk showed the opposite phenomenon. Heatmap cluster analysis indicated that camel milk was the most comparable to human milk before digestion, yet sheep milk was the most similar to human milk regarding protein digestion behaviors following infant gastric digestion.

Breastfeeding and impact on childhood hospital admissions: a nationwide birth cohort in South Korea

Benefits of breastfeeding for both the mother and the child are well established, but a comprehensive and robust study to investigate the protective effect of breastfeeding and attenuated time effect stratified by cause of morbidity are lacking. This study is based on the nationwide birth cohort in Korea that includes data on all infants born from 2009 to 2015. Of 1,608,540 children, the median follow-up period was 8.41 years (interquartile range, 6.76-10.06). When compared to children with fully formula feeding, the hospital admission rate was 12% lower in those with partially breastfeeding and 15% lower in those with exclusive breastfeeding. The apparent protective effect of breastfeeding was reduced with increasing age. Our study provides potential evidence of the beneficial association of breastfeeding on subsequent hospital admissions. The protective effect declined over time as the children grew older. Encouraging any breastfeeding for at least the first 6 months among infants is an important public health strategy to improve overall child health.

Dilemmas and options for COVID-19 vaccination in children

Over 16 million children have been detected positive for the coronavirus disease 2019 (COVID-19) in the United States since the outbreak of the pandemic. In general, children infected with severe acute respiratory syndrome coronavirus type 2 tend to have lighter symptoms than adults. However, in some cases, the infection can develop into severe forms, such as multisystem inflammatory syndrome in children. Moreover, long-term public health preventive interventions have had some negative effects on the physical and mental health of children. Given the important role that vaccination plays in reducing severe illness and mortality, it is essential for the efficient implementation of vaccination in the pediatric population. Nevertheless, parental distrust of vaccination, especially with regard to its safety and efficacy, hinders this process. Herein, we comprehensively summarize the available data on the safety and effectiveness of COVID-19 vaccine in children. The results show that the currently approved COVID-19 vaccine is safe and effective for children. Although two doses of vaccine in children seem insufficient to prevent Omicron infection, the booster dose provides enhanced protection against infection and severe illness. Most importantly, the bivalent vaccine has been approved for use in the pediatric population to extend the immune response to currently circulating Omicron variant. And the immune protection afforded to newborns after maternal vaccination appears to last only 6 months. Therefore, in the current situation where the rate of virus mutation is accelerating and the COVID-19 pandemic is still severe, it is crucial to extend vaccine protection to children over 6 months of age to weave a tighter safety net.

Development of Gut Microbiota in the First 1000 Days after Birth and Potential Interventions

The first 1000 days after birth represent a critical window for gut microbiome development, which is essential for immune system maturation and overall health. The gut microbiome undergoes major changes during this period due to shifts in diet and environment. Disruptions to the microbiota early in life can have lasting health effects, including increased risks of inflammatory disorders, autoimmune diseases, neurological disorders, and obesity. Maternal and environmental factors during pregnancy and infancy shape the infant gut microbiota. In this article, we will review how maintaining a healthy gut microbiome in pregnancy and infancy is important for long-term infant health. Furthermore, we briefly include fungal colonization and its effects on the host immune function, which are discussed as part of gut microbiome ecosystem. Additionally, we will describe how potential approaches such as hydrogels enriched with prebiotics and probiotics, gut microbiota transplantation (GMT) during pregnancy, age-specific microbial ecosystem therapeutics, and CRISPR therapies targeting the gut microbiota hold potential for advancing research and development. Nevertheless, thorough evaluation of their safety, effectiveness, and lasting impacts is crucial prior to their application in clinical approach. The article emphasizes the need for continued research to optimize gut microbiota and immune system development through targeted early-life interventions.

The Secretory IgA Response in Human Milk Against the SARS-CoV-2 Spike Is Highly Durable and Neutralizing for At Least 1 Year of Lactation Postinfection

Background: Although in the early pandemic period COVID-19 pathology among young children and infants was typically less severe compared with that observed among adults, this has not remained entirely consistent as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have emerged. There is an enormous body of evidence demonstrating the benefits of human milk antibodies (Abs) in protecting infants against a wide range of enteric and respiratory infections. It is highly plausible that the same holds true for protection against SARS-CoV-2 as this virus infects cells of the gastrointestinal and respiratory mucosae. Understanding the durability of a human milk Ab response over time after infection is critical. Objective: Previously, we examined the Abs present in milk of those recently infected with SARS-CoV-2 and concluded that the response was secretory immunoglobulin A (sIgA) dominant and that these titers were highly correlated with neutralization potency. The present study aimed to monitor the durability of the SARS-CoV-2 IgA and secretory Ab (sAb) response in milk from COVID-19-recovered lactating individuals over 12 months in the absence of vaccination or reinfection. Results: This analysis revealed a robust and durable spike-specific milk sIgA response, and at 9-12 months after infection, 88% of the samples exhibited titers above the positive cutoff for IgA and 94% were above the cutoff for sAb. Fifty percent of participants exhibited less than twofold reduction of spike-specific IgA through 12 months. A strong, significant positive correlation between IgA and sAb against spike persisted throughout the study period. Nucleocapsid-specific Abs were also assessed, which revealed significant background or cross-reactivity of milk IgA against this immunogen, as well as limited/inconsistent durability compared with Spike titers. Conclusion: These data suggest that lactating individuals are likely to continue producing spike-specific Abs in their milk for 1 year or more, which may provide critical passive immunity to infants against SARS-CoV-2 throughout the lactation period.

Impact of maternal SARS-CoV-2 booster vaccination on blood and breastmilk antibodies

Maternal COVID-19 vaccination could protect infants who are ineligible for vaccine through antibody transfer during pregnancy and lactation. We measured the quantity and durability of SARS-CoV-2 antibodies in human milk and infant blood before and after maternal booster vaccination. Prospective cohort of lactating women immunized with primary and booster COVID-19 vaccines during pregnancy or lactation and their infants. Milk and blood samples from October 2021 to April 2022 were included. Anti-nucleoprotein (NP) and anti-receptor binding domain (RBD) IgG and IgA in maternal milk and maternal and infant blood were measured and compared longitudinally after maternal booster vaccine. Forty-five lactating women and their infants provided samples. 58% of women were anti-NP negative and 42% were positive on their first blood sample prior to booster vaccine. Anti-RBD IgG and IgA in milk remained significantly increased through 120-170 days after booster vaccine and did not differ by maternal NP status. Anti-RBD IgG and IgA did not increase in infant blood after maternal booster. Of infants born to women vaccinated in pregnancy, 74% still had positive serum anti-RBD IgG measured on average 5 months after delivery. Infant to maternal IgG ratio was highest for infants exposed to maternal primary vaccine during the second trimester compared to third trimester (0.85 versus 0.29; p<0.001). Maternal COVID-19 primary and booster vaccine resulted in robust and long-lasting transplacental and milk antibodies. These antibodies may provide important protection against SARS-CoV-2 during the first six months of life.

Assessment of human milk samples obtained pre and post-influenza vaccination reveals a poor boosting of seasonally-relevant, hemagglutinin-specific antibodies

Introduction

Influenza (flu) vaccination prevented over 100,000 hospitalizations and 7000 deaths from flu over the 2019-2020 season in the USA. Infants <6 months are the most likely to die from flu, though flu vaccines are only licensed for infants >6 months old. Therefore, it is recommended that flu vaccination occur during pregnancy, as this reduces severe complications; however, vaccination rates are suboptimal, and vaccination is also recommended postpartum. For breast/chest-fed infants, the vaccine is believed to elicit protective and robust seasonally-specific milk antibody (Ab). Few comprehensive studies exist examining Ab responses in milk after vaccination, with none measuring secretory Ab (sAb). Determining whether sAbs are elicited is critical, as this Ab class is highly stable in milk and mucosae.

Methods

In the present study, our aim was to determine to what extent specific Ab titers in the milk of lactating people were boosted after seasonal influenza vaccination. Over the 2019-2020 and 2020-2021 seasons, milk was obtained pre- and post-vaccination and assessed for specific IgA, IgG, and sAb against relevant hemagglutinin (HA) antigens by a Luminex immunoassay.

Results

IgA and sAb were not found to be significantly boosted, while only IgG titers against B/Phuket/3073/2013, included in vaccines since 2015, exhibited an increase. Across the 7 immunogens examined, as many as 54% of samples exhibited no sAb boost. No significant differences for IgA, sAb, or IgG boosting were measured between seasonally-matched versus mismatched milk groups, indicating boosting was not seasonally-specific. No correlations between IgA and sAb increases were found for 6/8 HA antigens. No boost in IgG- or IgA-mediated neutralization post vaccination was observed.

Discussion

This study highlights the critical need to redesign influenza vaccines with the lactating population in mind, wherein the aim should be to elicit a potent seasonally-specific sAb response in milk. As such, this population must be included in clinical studies.

The secretory IgA (sIgA) response in human milk against the SARS-CoV-2 Spike is highly durable and neutralizing for at least 1 year of lactation post-infection

Although in the early pandemic period, COVID-19 pathology among young children and infants was typically less severe compared to that observed among adults, this has not remained entirely consistent as SARS-CoV-2 variants have emerged. There is an enormous body of evidence demonstrating the benefits of human milk antibodies (Abs) in protecting infants against a wide range of enteric and respiratory infections. It is highly plausible that the same holds true for protection against SARS-CoV-2, as this virus infects cells of the gastrointestinal and respiratory mucosae. Understanding the durability of a human milk Ab response over time after infection is critical. Previously, we examined the Abs present in milk of those recently infected with SARS-CoV-2, and concluded that the response was secretory IgA (sIgA)-dominant and that these titers were highly correlated with neutralization potency. The present study aimed to monitor the durability of the SARS-CoV-2 IgA and secretory Ab (sAb) response in milk from COVID-19-recovered lactating individuals over 12 months, in the absence of vaccination or re-infection. This analysis revealed a robust and durable Spike-specific milk sIgA response, that at 9-12 months after infection, 88% of the samples exhibited titers above the positive cutoff for IgA and 94% were above cutoff for sAb. Fifty percent of participants exhibited less than a 2-fold reduction of Spike-specific IgA through 12 months. A strong significant positive correlation between IgA and sAb against Spike persisted throughout the study period. Nucleocapsid-specific Abs were also assessed, which revealed significant background or cross reactivity of milk IgA against this immunogen, as well as limited/inconsistent durability compared to Spike titers. These data suggests that lactating individuals are likely to continue producing Spike-specific Abs in their milk for 1 year or more, which may provide critical passive immunity to infants against SARS-CoV-2 throughout the lactation period.

Nutrition, Gut Microbiota, and Allergy Development in Infants

The process of gut microbiota development in infants is currently being challenged by numerous factors associated with the contemporary lifestyle, including diet. A thorough understanding of all aspects of microbiota development will be necessary for engineering strategies that can modulate it in a beneficial direction. The long-term consequences for human development and health of alterations in the succession pattern that forms the gut microbiota are just beginning to be explored and require much further investigation. Nevertheless, it is clear that gut microbiota development in infancy bears strong associations with the risk for allergic disease. A useful understanding of microbial succession in the gut of infants needs to reveal not only changes in taxonomic composition but also the development of functional capacities through time and how these are related to diet and various environmental factors. Metagenomic and metatranscriptomic studies have started to produce insights into the trends of functional repertoire and gene expression change within the first year after birth. This understanding is critical as during this period the most substantial development of the gut microbiota takes place and the relations between gut microbes and host immunity are established. However, further research needs to focus on the impact of diet on these changes and on how diet can be used to counteract the challenges posed by modern lifestyles to microbiota development and reduce the risk of allergic disease.

Microbiome-Immune Interactions in Allergy and Asthma

The human microbiota has been established as a key regulator of host health, in large part owing to its constant interaction with and impact on host immunity. A range of environmental exposures spanning from the prenatal period through adulthood are known to affect the composition and molecular productivity of microbiomes across mucosal and dermal tissues with short- and long-term consequences for host immune function. Here we review recent findings in the field that provide insights into how microbial-immune interactions promote and sustain immune dysfunction associated with allergy and asthma. We consider both early life microbiome perturbation and the molecular underpinnings of immune dysfunction associated with subsequent allergy and asthma development in childhood, as well as microbiome features that relate to phenotypic attributes of allergy and asthma in older patients with established disease.

Maternal vaccination as an additional approach to improve the protection of the nursling: Anti-infective properties of breast milk

Human milk constitutes a secretion with unique functions of both nourishing the nursling and providing protection against enteric and respiratory infections, mainly due to its content of secretory IgA antibodies but also due to the presence of a plethora of bioactive factors. Specific IgA antibodies are produced locally by plasma cells derived from B lymphocytes that migrate from other mucosae to the mammary gland during lactation, particularly from the gastrointestinal and respiratory tracts. Therefore, here, the authors will provide a comprehensive review of the content and functions of different nutritional and bioactive anti-infectious components from breast milk, such as oligosaccharides, lactoferrin, haptocorrin, α-lactalbumin, k-casein, lysozyme, lactoperoxidase, mucin, fatty acids, defensins, cytokines and chemokines, hormones and growth factors, complement proteins, leukocytes and nucleic acids, including microRNAs, among many others, and the induction of antibody responses in breast milk after maternal vaccination with several licensed vaccines, including the anti-SARS-CoV-2 vaccine preparations used worldwide. Currently, in the midst of the pandemic, maternal vaccination has re-emerged as a crucial source of passive immunity to the neonate through the placenta and breastfeeding, considering that maternal vaccination can induce specific antibodies if performed during pregnancy and after delivery. There have been some reports in the literature about milk IgA antibodies induced by bacterial antigens or inactivated virus vaccines, such as anti-diphtheria-tetanus-pertussis, anti-influenza viruses, anti-pneumococcal and meningococcal polysaccharide preparations. Regarding anti-SARS-CoV-2 vaccines, most studies demonstrate elevated levels of specific IgA and IgG antibodies in milk with virus-neutralizing ability after maternal vaccination, which represents an additional approach to improve the protection of the nursling during the entire breastfeeding period.

Roles of Secretory Immunoglobulin A in Host-Microbiota Interactions in the Gut Ecosystem

In the gastrointestinal tract (GIT), the immune system interacts with a variety of microorganisms, including pathogens as well as beneficial symbionts that perform important physiological functions for the host and are crucial to sustain intestinal homeostasis. In normal conditions, secretory immunoglobulin A (SIgA) is the principal antibody produced by B cells in the GIT mucosa. Polyreactivity provides certain SIgA molecules with the ability of binding different antigens in the bacterial surface, such as O-antigens and teichoic acids, while cross-species reactivity allows them to recognize and interact with different types of bacteria. These functions may be crucial in allowing SIgA to modulate the complex gut microbiota in an efficient manner. Several studies suggest that SIgA can help with the retention and proliferation of helpful members of the gut microbiota. Gut microbiota alterations in people with IgA deficiency include the lack of some species that are known to be normally coated by SIgA. Here, we discuss the different ways in which SIgA behaves in relation to pathogens and beneficial bacteria of the gut microbiota and how the immune system might protect and facilitate the establishment and maintenance of certain gut symbionts.

Secretory IgA: Linking microbes, maternal health, and infant health through human milk

Secretory immunoglobulin A (SIgA) in human milk plays a central role in complex maternal-infant interactions that influence long-term health outcomes. Governed by genetics and maternal microbial exposure, human milk SIgA shapes both the microbiota and immune system of infants. Historically, SIgA-microbe interactions have been challenging to unravel due to their dynamic and personalized nature, particularly during early life. Recent advances have helped to clarify how SIgA acts beyond simple pathogen clearance to help guide and constrain a healthy microbiota, promote tolerance, and influence immune system development. In this review, we highlight these new findings in the context of the critical early-life window and propose outstanding areas of study that will be key to harnessing the benefits of SIgA to support healthy immune development during infancy.

Molecular alterations in human milk in simulated maternal nasal mucosal infection with live attenuated influenza vaccination

Breastfeeding protects against mucosal infections in infants. The underlying mechanisms through which immunity develops in human milk following maternal infection with mucosal pathogens are not well understood. We simulated nasal mucosal influenza infection through live attenuated influenza vaccination (LAIV) and compared immune responses in milk to inactivated influenza vaccination (IIV). Transcriptomic analysis was performed on RNA extracted from human milk cells to evaluate differentially expressed genes and pathways on days 1 and 7 post-vaccination. Both LAIV and IIV vaccines induced influenza-specific IgA that persisted for at least 6 months. Regulation of type I interferon production, toll-like receptor, and pattern recognition receptor signaling pathways were highly upregulated in milk on day 1 following LAIV but not IIV at any time point. Upregulation of innate immunity in human milk may provide timely protection against mucosal infections until antigen-specific immunity develops in the human milk-fed infant.

The prospect of orally administered monoclonal secretory IgA (SIgA) antibodies to prevent enteric bacterial infections

Eliminating diarrheal diseases as a leading cause of childhood morbidity and mortality in low- and middle-income countries (LMICs) will require multiple intervention strategies. In this review, we spotlight a series of preclinical studies investigating the potential of orally administered monoclonal secretory IgA (SIgA) antibodies (MAbs) to reduce disease associated with three enteric bacterial pathogens: Campylobacter jejuni, enterotoxigenic Escherichia coli (ETEC), and invasive Salmonella enterica serovar Typhimurium. IgA MAbs targeting bacterial surface antigens (flagella, adhesins, and lipopolysaccharide) were generated from mice, humanized mice, and human tonsillar B cells. Recombinant SIgA1 and/or SIgA2 derivates of those MAbs were purified from supernatants following transient transfection of 293 cells with plasmids encoding antibody heavy and light chains, J-chain, and secretory component (SC). When administered to mice by gavage immediately prior to (or admixed with) the bacterial challenge, SIgA MAbs reduced infection C. jejuni, ETEC, and S. Typhimurium infections. Fv-matched IgG1 MAbs by comparison were largely ineffective against C. jejuni and S. Typhimurium under the same conditions, although they were partially effective against ETEC. While these findings highlight future applications of orally administered SIgA, the studies also underscored the fundamental challenges associated with using MAbs as prophylactic tools against enteric bacterial diseases.

Human Breast Milk: From Food to Active Immune Response With Disease Protection in Infants and Mothers

Breastfeeding is associated with long-term wellbeing including low risks of infectious diseases and non-communicable diseases such as asthma, cancer, autoimmune diseases and obesity during childhood. In recent years, important advances have been made in understanding the human breast milk (HBM) composition. Breast milk components such as, non-immune and immune cells and bioactive molecules, namely, cytokines/chemokines, lipids, hormones, and enzymes reportedly play many roles in breastfed newborns and in mothers, by diseases protection and shaping the immune system of the newborn. Bioactive components in HBM are also involved in tolerance and appropriate inflammatory response of breastfed infants if necessary. This review summarizes the current literature on the relationship between mother and her infant through breast milk with regard to disease protection. We will shed some light on the mechanisms underlying the roles of breast milk components in the maintenance of health of both child and mother.

Chrononutrition and Human Milk

Background

Breastfed infants have a reduced risk of infections and allergies. The study of chrononutrition in human milk seeks to understand the circadian variation of various human milk immune factors.

Methods

Empirical studies on human milk, chrononutrition, and immune factors were searched through PUBMED, Google Scholar, and SCOPUS. Keywords included “chrononutrition,” “breastmilk composition,” “human milk,” “day-night cycles,” “sleep-wake cycles” and the names of various immune factors. After excluding duplicate articles, animal studies, studies looking at other human milk components, studies that did not collect human milk samples over a 24 hour period, and studies that were not in English, eleven studies on the topic remained and ten studies were included in the review. The excluded study had a sample size of two.

Results

This review identified the circadian variation of certain immune factors found in human milk such as antibodies, complement proteins, cytokines, by-products of phagocyte activity, nucleotides, microRNAs, and antioxidants.

Conclusion

The circadian variation observed in some human milk components highlights the unique ability of human milk to vary in composition based on the circadian rhythms of mothers and infants. The limited number of studies makes it difficult to make conclusive recommendations and creates an opportunity for further research in this growing field.

Oropharyngeal administration of mother's own milk influences levels of salivary sIgA in preterm infants fed by gastric tube

The aim of the present study was to explore the effect of oropharyngeal mother’s milk administration on salivary secretory immunoglobulin A (sIgA) levels in preterm infants fed by gastric tube. Infants (n = 130) with birth weight < 1500 g were randomly allocated into two groups which both received breast milk for enteral nutrition. The experimental group (n = 65) accepted oropharyngeal mother’s milk administration before gastric tube feeding for 14 days after birth. The control group (n = 65) accepted oropharyngeal 0.9% normal saline administration. Saliva concentration of sIgA were assessed at the 2 h, 7th and 14th day after birth. The level of salivary sIgA in experimental group were significantly higher than those in control group on the 7th day after birth (p < 0.05), but there were no differences in salivary sIgA levels on the 14th day between the two groups. The results of quantile regression analysis showed that oropharyngeal mother’s milk administration, delivery mode and gestational age had significant effects on the increase of sIgA. SIgA in experimental group and the total number of intervention had a significant positive correlation (p < 0.05). Oropharyngeal mother’s milk administration can improve salivary sIgA levels of preterm infants.

Salmonella Uptake into Gut-Associated Lymphoid Tissues: Implications for Targeted Mucosal Vaccine Design and Delivery

Peyer's patches are organized gut-associated lymphoid tissues (GALT) in the small intestine and the primary route by which particulate antigens, including viruses and bacteria, are sampled by the mucosal immune system. Antigen sampling occurs through M cells, a specialized epithelial cell type located in the follicle-associated epithelium (FAE) that overlie Peyer's patch lymphoid follicles. While Peyer's patches play an integral role in intestinal homeostasis, they are also a gateway by which enteric pathogens, like Salmonella enterica serovar Typhimurium (STm), cross the intestinal barrier. Once pathogens like STm gain access to the underlying network of mucosal dendritic cells and macrophages they can spread systemically. Thus, Peyer's patches are at the crossroads of mucosal immunity and intestinal pathogenesis. In this chapter, we provide detailed methods to assess STm entry into mouse Peyer's patch tissues. We describe Peyer's patch collection methods and provide strategies to enumerate bacterial uptake. We also detail a method for quantifying bacterial shedding from infected animals and provide an immunohistochemistry protocol for the localization of STm along the gastrointestinal tract and insight into pathogen transit in the presence of protective antibodies. While the protocols are written for STm, they are easily tailored to other enteric pathogens.

Determinants of Early Initiation of Breastfeeding in West Belessa District, Northwest Ethiopia

BACKGROUND

The world is now suffering from malnutrition and remains one of the leading causes of death for under 5 children. Children from developing countries, including Ethiopia also suffer from undernutrition due to suboptimal breastfeeding practice. Therefore, the aim of this study was to assess the EIBF practices and determinants among children aged less than 24 months in West Belessa district, Northwest Ethiopia, 2019.

METHODS

A community-based cross-sectional study was conducted from January 2 to February 28, 2019 in the West Belessa district. A total of 569 mother-children pairs were participated in the study. Study particnapants were selected by using simple random sampling technique. The data were collected by an interviewer-administered structured questionnaire. Data were entered and analyzed by using Epi-Info version 7 and SPPS version 20, respectively. Bi-variable and Multivariable logistic regression analysis were done. Odds ratio with 95% confidence was done to determine the level of significance value less than .05 considered as significant with the outcome variable.

RESULT

The prevalence of early initiation of breastfeeding (EIBF) was found to be 77.7 % (95%CI, 74.3-81.0). Age of the mother (AOR = 2.76, 95%CI [1.21, 6.27]), antenatal care (ANC) (AOR = 3.79, 95%CI [2.58, 9.94]), and number of antenatal care visit (AOR = 1.85, 95%CI [1.03, 3.85]) were significantly associated with early initiation of breastfeeding.

CONCLUSION AND RECOMMENDATION

In this study, more than three fourth of children were received early initiation of breastfeeding within 1 hour after delivery. Age of the mother, antenatal, and number of antenatal care were associated with EIBF. Therefore, during this contact period, improve antenatal services by increasing accessibility and providing counseling is important to improve EIBF utilization.

The role of allergen-specific IgE, IgG and IgA in allergic disease

Immunoglobulin E (IgE)‐mediated allergy is the most common hypersensitivity disease affecting more than 30% of the population. Exposure to even minute quantities of allergens can lead to the production of IgE antibodies in atopic individuals. This is termed allergic sensitization, which occurs mainly in early childhood. Allergen‐specific IgE then binds to the high (FcεRI) and low‐affinity receptors (FcεRII, also called CD23) for IgE on effector cells and antigen‐presenting cells. Subsequent and repeated allergen exposure increases allergen‐specific IgE levels and, by receptor cross‐linking, triggers immediate release of inflammatory mediators from mast cells and basophils whereas IgE‐facilitated allergen presentation perpetuates T cell–mediated allergic inflammation. Due to engagement of receptors which are highly selective for IgE, even tiny amounts of allergens can induce massive inflammation. Naturally occurring allergen‐specific IgG and IgA antibodies usually recognize different epitopes on allergens compared with IgE and do not efficiently interfere with allergen‐induced inflammation. However, IgG and IgA antibodies to these important IgE epitopes can be induced by allergen‐specific immunotherapy or by passive immunization. These will lead to competition with IgE for binding with the allergen and prevent allergic responses. Similarly, anti‐IgE treatment does the same by preventing IgE from binding to its receptor on mast cells and basophils. Here, we review the complex interplay of allergen‐specific IgE, IgG and IgA and the corresponding cell receptors in allergic diseases and its relevance for diagnosis, treatment and prevention of allergy.

Immune Response of Neonates Born to Mothers Infected With SARS-CoV-2

IMPORTANCE

Although several studies have provided information on short-term clinical outcomes in children with perinatal exposure to SARS-CoV-2, data on the immune response in the first months of life among newborns exposed to the virus in utero are lacking.

OBJECTIVE

To characterize systemic and mucosal antibody production during the first 2 months of life among infants who were born to mothers infected with SARS-CoV-2.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study enrolled 28 pregnant women who tested positive for SARS-CoV-2 infection and who gave birth at Policlinico Umberto I in Rome, Italy, from November 2020 to May 2021, and their newborns. Maternal and neonatal systemic immune responses were investigated by detecting spike-specific antibodies in serum, and the mucosal immune response was assessed by measuring specific antibodies in maternal breastmilk and infant saliva 48 hours after delivery and 2 months later.

EXPOSURES

Maternal infection with SARS-CoV-2 in late pregnancy.

MAIN OUTCOMES AND MEASURES

The systemic immune response was evaluated by the detection of SARS-CoV-2 IgG and IgA antibodies and receptor binding domain-specific IgM antibodies in maternal and neonatal serum. The mucosal immune response was assessed by measuring spike-specific antibodies in breastmilk and in infant saliva, and the presence of antigen-antibody spike IgA immune complexes was investigated in breastmilk samples. All antibodies were detected using an enzyme-linked immunosorbent assay.

RESULTS

In total, 28 mother-infant dyads (mean [SD] maternal age, 31.8 [6.4] years; mean [SD] gestational age, 38.1 [2.3] weeks; 18 [60%] male infants) were enrolled at delivery, and 21 dyads completed the study at 2 months' follow-up. Because maternal infection was recent in all cases, transplacental transfer of virus spike-specific IgG antibodies occurred in only 1 infant. One case of potential vertical transmission and 1 case of horizontal infection were observed. Virus spike protein-specific salivary IgA antibodies were significantly increased (P = .01) in infants fed breastmilk (0.99 arbitrary units [AU]; IQR, 0.39-1.68 AU) vs infants fed an exclusive formula diet (0.16 AU; IQR, 0.02-0.83 AU). Maternal milk contained IgA spike immune complexes at 48 hours (0.53 AU; IQR, 0.25-0.39 AU) and at 2 months (0.09 AU; IQR, 0.03-0.17 AU) and may have functioned as specific stimuli for the infant mucosal immune response.

CONCLUSIONS AND RELEVANCE

In this cohort study, SARS-CoV-2 spike-specific IgA antibodies were detected in infant saliva, which may partly explain why newborns are resistant to SARS-CoV-2 infection. Mothers infected in the peripartum period appear to not only passively protect the newborn via breastmilk secretory IgA but also actively stimulate and train the neonatal immune system via breastmilk immune complexes.

Allergen shedding in human milk: Could it be key for immune system education and allergy prevention?

In addition to being a source of nutrients for the developing newborn, human milk contains thousands of bioactive compounds, which influence infant health in the short-term as exemplified by its major benefits on infectious disease prevention. Many of the human milk compounds also have the required characteristics to instruct immune development and guide long-term health. Prebiotics, probiotics, and varied antimicrobial molecules all have the potential to shape the composition and function of the establishing gut microbiota, which is known to be a major determinant of immune function. Another and less explored way human milk can instruct long-term immunity is through antigen shedding. Here, we will review the evidence that antigens from maternal environment and more specifically from allergen sources are found in human milk. We will discuss data from rodent models and birth cohorts showing that allergen shedding in breast milk may influence long-term allergy risk. We will uncover the variables that may underlie heterogeneity in oral tolerance induction and allergy prevention in children breast-fed by allergen-exposed mothers. We will focus on the parameters that control antigen transfer to breast milk, on the unique biological characteristics of allergens in breast milk, and on the milk bioactive compounds that were found to influence immune response in offspring. We propose this understanding is fundamental to guide maternal interventions leading to lifelong allergen tolerance.

Delayed Initiation of Breastfeeding and Role of Mode and Place of Childbirth: Evidence from Health Surveys in 58 Low- and Middle- Income Countries (2012-2017)

Background: Timely initiation of breastfeeding is the first step towards achieving recommended breastfeeding behaviours. Delayed breastfeeding initiation harms neonatal health and survival, including infection associated neonatal mortality. Eighty percent of neonatal deaths occur in the low-and middle-income countries (LMICs), where delayed breastfeeding initiation is the highest. Place and mode of childbirth are important factors determining the time of initiation of breastfeeding. In this study, we report the prevalence of delayed breastfeeding initiation from 58 LMICs and investigate the relationship between place and mode of childbirth and delayed breastfeeding initiation in each country. Methods: We analysed data from the most recent Demographic and Health Survey (DHS) and Multiple Indicator Cluster Survey (MICS) collected between 2012 and 2017 and reported by 2019. The study sample comprised all women who had a live birth in the 24 months preceding the survey. ‘Delayed’ initiation of breastfeeding was defined using WHO recommendations as starting breastfeeding after one hour of birth. We coded the stratifying variable for the place and mode of childbirth as “vaginal birth at a facility (VBF)”, “caesarean section birth (CSB) “, and “vaginal birth at home (VBH)”. We used respondent-level sampling weights to account for individual surveys and de-normalised the standard survey weights to ensure the appropriate contribution of data from each country. We report the prevalence and population attributable fractions with robust standard errors. The population attributable risk identifies the proportion of delayed initiation that we could avert among VBH and CSB if everyone had the same risk of delaying breastfeeding as in VBF. Results: The overall prevalence of delayed initiation of breastfeeding was 53.8% (95% CI 53.3, 54.3), ranging from 15.0% (95% CI 13.8, 16.2) in Burundi to 83.4% (95% CI 80.6, 86.0) in Guinea. The prevalence of delayed initiation of breastfeeding was consistently high among women who experienced caesarean section births; however, there was no direct association with each country’s national caesarean section rates. The prevalence of delayed initiation among women who experienced VBF was high in Sub-Saharan Africa and South Asia, even though the CSB rates were low. In some countries, women who give birth vaginally in health facilities were more likely to delay breastfeeding initiation than women who did not. In many places, women who give birth by caesarean section were less likely to delay breastfeeding initiation. Population attributable risk percent for VBH ranged from −28.5% in Ukraine to 22.9% in Moldova, and for CSB, from 10.3% in Guinea to 54.8% in Burundi. On average, across all 58 countries, 24.4% of delayed initiation could be prevented if all women had the same risk of delaying breastfeeding initiation as in VBF. Discussion: In general, women who give birth in a health facility were less likely to experience delayed initiation of breastfeeding. Programs could avert much of the delayed breastfeeding initiation in LMICs if the prevalence of delayed initiation amongst women who experience CSB were the same as amongst women who experience VBF. Crucial reforms of health facilities are required to ensure early breastfeeding practices and to create pro-breastfeeding supportive environments as recommended in intervention packages like the Baby-friendly hospital initiative and Early essential newborn care. The findings from this study will guide program managers to identify countries at varying levels of preparedness to establish and maintain a breastfeeding-friendly environment at health facilities. Thus, governments should prioritise intervention strategies to improve coverage and settings surrounding early initiation of breastfeeding while considering the complex role of place and mode of childbirth.

The effects of probiotic supplementation on the gene expressions of immune cell surface markers and levels of antibodies and pro-inflammatory cytokines in human milk

OBJECTIVE

This study investigated the impact of probiotic supplementation on the gene expressions of cluster of differentiation (CD) as cell markers and the concentrations of antibodies and cytokines in human milk.

STUDY DESIGN

Gene expressions of CD28, CD19, and CD38 were determined in milk from 15 women ingesting daily probiotics (from Greek yogurt) and 12 women who do not consume probiotics. Concentrations of antibodies and cytokines were measured using ELISA.

RESULTS

Gene expression of CD28 tended to be higher in milk from mothers ingesting daily probiotics than mothers who did not take probiotics. Interleukin-6 (IL-6) concentration in milk was higher in mothers ingesting probiotics than those who do not consume probiotics. The increase of IL-6 level in human milk was positively correlated with total IgA and IgG concentrations.

CONCLUSIONS

Probiotic supplementation could enhance the secretion of IL-6 in human milk. Human milk IL-6 may improve neonatal immunity due to its stimulation of total IgA and IgG.

Milk and Dairy Products: Good or Bad for Human Bone? Practical Dietary Recommendations for the Prevention and Management of Osteoporosis

Osteoporosis affects women twice as often as men. Additionally, it is estimated that 0.3 million and 1.7 million people have hip fractures in the USA and Europe, respectively. Having a proper peak bone mass and keeping it as long as possible is especially important for osteoporosis prevention. One of the most important calcium sources is milk and dairy products. Breast milk is the best infant food, but milk should not be avoided later in life to prevent losing bone mass. On the other hand, more and more people limit their milk consumption and consume other dairy or non-dairy products. For example, they are usually replaced with plant beverages, which should be consumed carefully in several age groups. Additionally, an important element of milk and dairy products, as well as plant beverages, are probiotics and prebiotics, which may modulate bone turnover. Dietary recommendations focused on milk, and dairy products are an important element for the prevention of osteoporosis.

Antiviral Properties of Human Milk

Humans have always coexisted with viruses, with both positive and negative consequences. Evolutionary pressure on mammals has selected intrinsic properties of lactation and milk to support the relatively immunocompromised neonate from environmental pathogens, as well as support the normal development of diverse immune responses. Human milk supports both adaptive and innate immunity, with specific constituents that drive immune learning and maturation, and direct protection against microorganisms. Viruses constitute one of the most ancient pressures on human evolution, and yet there is a lack of awareness by both public and healthcare professionals of the complexity of human milk as an adaptive response beyond the production of maternal antibodies. This review identifies and describes the specific antiviral properties of human milk and describes how maternal support of infants through lactation is protective beyond antibodies.

Combination-Feeding Causes Differences in Aspects of Systemic and Mucosal Immune Cell Phenotypes and Functions Compared to Exclusive Sow-Rearing or Formula-Feeding in Piglets

Combination feeding (human milk and formula) is common and influences immune development compared to exclusive breastfeeding. Infant formulas contain prebiotics, which influence immune development. Herein, immune development of combination-fed (CF), sow-reared (SR) and formula-fed (FF) piglets, and the effect of prebiotics was tested. Piglets (n = 47) were randomized to: SR, FF, CF, FF+prebiotic (FP), and CF+prebiotic (CP). FP and CP received formula with galactooligosaccharides and inulin (4 g/L in a 4:1 ratio). CF and CP piglets were sow-reared for until d5 and then rotated between a sow and formula every 12 h. On day 21, piglets received an intraperitoneal injection of lipopolysaccharide 2 h prior to necropsy. Immune cells from blood, mesenteric lymph nodes (MLN), and spleen were phenotyped. Classical (nitric oxide synthase) and alternative (arginase activity) activation pathways were measured in isolated macrophages. Serum IL-6 and TNF-α were measured by ELISA. SR piglets had lower (p < 0.0001) CD4+ T-helper cells and higher (p < 0.0001) B-cells in PBMC than all other groups. CP piglets had higher (p < 0.0001) arginase activity compared to all other groups. FF piglets had higher (p < 0.05) IL-6 compared to both CF and SR, but were similar to FP and CP. Thus, CF, with or without prebiotics, differentially affected immunity compared to exclusively fed groups.

Timely initiation of breastfeeding and associated factors among mothers having children less than two years of age in sub-Saharan Africa: A multilevel analysis using recent Demographic and Health Surveys data

BACKGROUND

Despite the significant advantages of timely initiation of breastfeeding (TIBF), many countries particularly low- and middle-income countries have failed to initiate breastfeeding on time for their newborns. Optimal breastfeeding is one of the key components of the SDG that may help to achieve reduction of under-five mortality to 25 deaths per 1000 live births.

OBJECTIVE

To assess the pooled prevalence and associated factors of timely initiation of breastfeeding among mothers having children less than two years of age in sub-Saharan Africa.

METHODS

We used pooled data from the 35 sub-Saharan Africa (SSA) Demographic and Health Surveys (DHS). We used a total weighted sample of 101,815 women who ever breastfeed and who had living children under 2 years of age. We conducted the multilevel logistic regression and variables with p<0.05, in the multivariable analysis, were declared significantly associated with TIBF.

RESULTS

The pooled prevalence of TIBF in SSA was 58.3% [95%CI; 58.0-58.6%] with huge variation between countries, ranging from 24% in Chad to 86% in Burundi. Both individual and community level variables were associated with TIBF. Among individual-level factors; being older-aged mothers, having primary education, being from wealthier households, exposure to mass media, being multiparous, intended pregnancy, delivery at a health facility, vaginal delivery, single birth, and average size of the child at birth were associated with higher odds of TIBF. Of community-level factors, rural place of residence, higher community level of ANC utilization, and health facility delivery were associated with higher odds of TIBF.

CONCLUSION

In this study, the prevalence of TIBF in SSA was low. Both individual and community-level factors were associated with TIBF. The authors recommend interventions at both individual and community levels to increase ANC utilization as well as health facility delivery that are crucial for advertising optimal breastfeeding practices such as TIBF.

Breast Milk Virome and Bacterial Microbiome Resilience in Kenyan Women Living with HIV

Breast milk is nutritionally and immunologically beneficial in early life but is also a potential source of infection. Little is known about breast milk microbiota of women living with HIV (WLHIV), the impact of severe immunosuppression, and the contribution to mortality of HIV-exposed infants. Here, we performed metagenomic sequencing to characterize the bacterial microbiome and DNA virome of breast milk samples at 1 month postpartum from Kenyan WLHIV who were not receiving combination antiretroviral therapy (cART), 23 women with CD4 counts of <250 and 30 women with CD4 of >500; and additionally, 19 WLHIV with infants that lived and 26 WLHIV with infants that died during the first 2 years of life were included. We found that breast milk bacterial microbiomes in this study population were highly diverse but shared a core community composed of the Streptococcaceae, Staphylococcaceae, Moraxellaceae, and Eubacteriaceae families. The breast milk virome was dominated by human cytomegalovirus (CMV) and included the bacteriophage families Myoviridae, Siphoviridae, and Podoviridae. Bacterial microbiome and virome profiles and diversity were not significantly altered by HIV immunosuppression, as defined by a CD4 of <250. CMV viral load was not associated with maternal CD4 counts or infant mortality. In conclusion, we show that the core bacterial and viral communities are resilient in breast milk despite immunosuppression in WLHIV.

IMPORTANCE Breastfeeding plays an important role in seeding the infant gut microbiome and mammary health. Although most studies focus on the diverse breast milk bacterial communities, little is known about the viral communities harbored in breast milk. We performed the first breast milk virome study of an HIV population. In this study cohort of Kenyan women living with HIV from the pre-antiretroviral therapy era, we found that breast milk harbors a core bacterial microbiome and a virome dominated by human cytomegalovirus. The virome and bacterial microbiome were not substantially altered by immunosuppression or associated with infant mortality. Together, these findings indicate resilience of the microbial community in breast milk compartmentalization. These findings advance out fundamental understanding of the breast milk core microbiome and virome interactions in the context of HIV disease.

The multifaceted roles of breast milk antibodies

Neonates are born with an immature immune system and rely on the transfer of immunity from their mothers. Maternal antibodies are transferred via the placenta and breast milk. Although the role of placentally transferred immunoglobulin G (IgG) is established, less is known about the selection of antibodies transferred via breast milk and the mechanisms by which they provide protection against neonatal disease. Evidence suggests that breast milk antibodies play multifaceted roles, preventing infection and supporting the selection of commensals and tolerizing immunity during infancy. Here, we discuss emerging data related to the importance of breast milk antibodies in neonatal immunity and development.

Outcomes improved with human milk intake in preterm and full-term infants

This review highlights clinical outcomes of human milk from infancy through adulthood. Human milk outcomes of both preterm and term infants, including critically ill term infants (such as infants with congenital heart disease and those requiring therapeutic hypothermia) are summarized. Several human milk diets are identified to reduce the risk of specific diseases. Emerging research of newly discovered components of human milk are also reviewed. Human milk has significant effects on the gut microbiome, somatic growth, and neurocognitive outcomes. Continued research promises to improve donor human milk and donor milk derived products to achieve better outcomes for infants who do not receive their own mother's milk. The promotion of human milk is well-founded on evidence from the previous half century.

The "weanling's dilemma" revisited: Evolving bodies of evidence and the problem of infant paleodietary interpretation

Breastfeeding is known to be a powerful mediator of maternal and childhood health, with impacts throughout the life course. Paleodietary studies of the past 30 years have accordingly taken an enduring interest in the health and diet of young children as a potential indicator of population fertility, subsistence, and mortality patterns. While progress has been made in recent decades toward acknowledging the agency of children, many paleodietary reconstructions have failed to incorporate developments in cognate disciplines revealing synergistic dynamics between maternal and offspring biology. Paleodietary interpretation has relied heavily on the "weanling's dilemma," in which infants are thought to face a bleak choice between loss of immunity or malnutrition. Using a review of immunological and epidemiological evidence for the dynamic and supportive role that breastfeeding plays throughout the complementary feeding period, this article offers context and nuance for understanding past feeding transitions. We suggest that future interpretative frameworks for infant paleodietary and bioarchaeological research should include a broad knowledge base that keeps pace with relevant developments outside of those disciplines.

Effects of Holder Pasteurization on Immune Composition of Human Milk

Background: Human milk (HM) is the ideal food for newborn (NB) nutrition, it provides all macro and micronutrients for human growth and development and also contains bioactive compounds, which influence the development of the neonatal digestive and immune systems. The holder pasteurization process is essential to prevent NB infection from donated milk. Therefore, the aim of this study was to check whether or not holder pasteurization could impact the concentration of immune components in HM and the capacity to induce epithelial cell growth. Materials and Methods: The study was performed on raw and holder pasteurized (62.5°C/30 minutes) paired milk samples after submission to the freezing process in both phases. For cytokine and adipokine measurements, ELISA was performed on 40 individual samples of HM from single donors. For analyzes of epithelial cell growth, HuTu-80 cells were cultivated in Minimum Essential Eagle medium with 15% of raw or pasteurized milk, eight pairs of milk were used. Results: The results showed that no alteration was observed in the concentration of cytokine after milk holder pasteurization, and leptin concentration was reduced in holder pasteurized milk. The heat treatment also did not impact the capacity of breast milk to promote intestinal epithelial cell growth. Conclusions: The results showed that donated breast milk pasteurization has a small impact on the HM bioactive concentration compounds. This technique is important to avoid NB infection.

Immunomodulatory Constituents of Human Donor Milk

Mother's own human milk is the best nutrition for infants, especially preterm very-low-birth-weight (VLBW) (≤1,500 g) infants, because of its immune-modulatory constituents that strengthen the infant's host defense, provide protection against infections, and decrease the risk of necrotizing enterocolitis (NEC). When mother's own milk is unavailable or insufficient, donor human milk is considered the best alternative, especially for preterm VLBW infants. However, to assure biological safety, donor milk must be pasteurized. This results in partial or complete inactivation of some of the immunomodulatory constituents of human milk, which confer host defense. This review summarizes the current evidence regarding the effects of pasteurization on the different immunological constituents of donor milk, and their clinical significance, especially in relation to prevention of NEC.

Changes in Human Milk Immunoglobulin Profile During Prolonged Lactation

Mother's milk immunoglobulins (Igs) delivered to infants during breastfeeding are crucial in shaping and modulating immature infants' immune system and provide efficient protection against pathogens. The aim of the study was to evaluate the immunoglobulin concentrations in milk of 116 lactating mothers over prolonged lactation from the 1st to the 48th month using the ELISA method. The concentration of proteins, SIgA and IgG, but not IgM, showed a positive correlation (r = 0.69, p < 0.005; r = 0.54, p < 0.05; and r = 0.27, p < 0.05, respectively) with lactation from the 1st to the 48th month. The lowest concentrations of SIgA and IgG were observed for the first year (2.12 ± 0.62 g/L and 14.71 ± 6.18 mg/L, respectively) and the highest after the 2nd year of lactation (7.55 ± 7.16 g/L and 18.95 ± 6.76 mg/L, respectively). The IgM concentration remained stable during 2 years (2.81 ± 2.74 mg/L), but after 24 months it was higher (3.82 ± 3.05 mg/L), although not significantly. Moreover, negative correlations of protein (r = -0.24, p < 0.05) and SIgA (r = -0.47, p < 0.05) concentrations with the number of feedings were found. Human milk after the 2nd year of lactation contains significantly higher concentrations of protein, SIgA, and IgG. High concentration of immunoglobulins and protein during prolonged lactation is an additional argument to support breastfeeding even after introducing solid foods and should be one of the overarching goals in the protection of children's health.

The Anti-Inflammatory Properties of the Topical Application of Human Milk in Dermal and Optical Diseases

Methods

The various datasets including Ovid, PubMed, Google Scholar, Science Direct, Magiran, Irandoc, SID, and IranMedex were searched from 1990 to 2018. From the 119 reviewed articles, 20 articles were selected to be included in the current article.

Results

There is a consensus among the literature and ancient texts regarding the effectiveness of THM in curing the various types of skin damages, such as cord separation, atopic dermatitis, diaper dermatitis, conjunctivitis, scratches, insect bite, perineal ulcer, and nipple ulcer. However, the importance of its application has not been given much attention.

Conclusion

According to the information obtained from the articles reviewed, the THM appears to be an effective, safe, and available treatment compared to conventional chemical treatments. This study suggests THM as an alternative remedy to minimize the frequent use of chemical-based treatments. More research may be beneficial to reach certainty in terms of curative properties of THM in similar or different injuries in different populations.

Transmission of CMV, HTLV-1, and HIV through breastmilk

Breastfeeding is a crucial child survival intervention. However, the potential for transmission of viral infections from mother to child presents the dilemma of how best to interpret the benefits and risks of breastfeeding in different settings. In this Review, we compare the transmission dynamics, risk factors, and outcomes of infection with three chronic viruses transmitted through breastmilk: cytomegalovirus, human T-cell lymphotropic virus type 1, and HIV. We provide an overview of intervention approaches and discuss scientific, policy, and programming gaps in the understanding of these major global infections.

Rethinking mucosal antibody responses: IgM, IgG and IgD join IgA

Humoral immune responses at mucosal surfaces have historically focused on IgA. Growing evidence highlights the complexity of IgA-inducing pathways and the functional impact of IgA on mucosal commensal bacteria. In the gut, IgA contributes to the establishment of a mutualistic host-microbiota relationship that is required to maintain homeostasis and prevent disease. This Review discusses how mucosal IgA responses occur in an increasingly complex humoral defence network that also encompasses IgM, IgG and IgD. Aside from integrating the protective functions of IgA, these hitherto neglected mucosal antibodies may strengthen the communication between mucosal and systemic immune compartments.

Binding and Neutralizing Capacity of Respiratory Syncytial Virus (RSV)-Specific Recombinant IgG Against RSV in Human Milk, Gastric and Intestinal Fluids from Infants

Oral administration of pathogen-specific recombinant antibodies may help to prevent infant gastrointestinal (GI) pathogen infection; however, to neutralize an infectious agent, these antibodies must resist degradation in the GI tract. Palivizumab, a recombinant antibody specific for the respiratory syncytial virus (RSV), was used as a model for pathogen-specific IgG in human milk. The aim was to compare the remaining binding capacity of palivizumab in milk between three mothers after exposure to an in vitro model of infant gastrointestinal digestion (gastric and duodenal fluids) using ELISA. The neutralizing capacity of palivizumab in pooled human milk, gastric contents, and stools from preterm infants was also evaluated for blocking RSV with green fluorescent protein (RSV-GFP) infection in Hep-2 cells using confocal and inverted microscopy and flow cytometry. The reduction of palivizumab binding capacity in human milk and digested samples was slightly different between mothers. Overall, palivizumab decreased 50% after simulated gastric digestion with pepsin and 62% after simulated intestinal digestion with pancreatin. Palivizumab (2–8 μg/mL) in human milk or stool samples blocked RSV (3.4 × 10⁴ FFU/mL) infection (no syncytia formation on Hep-2 cells) by microscopy. Syncytia formation was detected on Hep-2 cells when RSV was incubated in gastric contents or virus medium with 2–4 μg/mL of palivizumab, but no infection was observed at 8 μg/mL. No fluorescence (absence of infected cells) was detected when palivizumab (100 μg/mL) was incubated in human milk or medium with RSV-GFP (1.1 × 10⁵ FFU/mL), whereas fluorescence increased with the reduced concentration of palivizumab using flow cytometry. These results suggest that undigested and digested matrices could change the binding and neutralizing capacity of viral pathogen-specific antibodies.

A Lactococcus lactis-vectored oral vaccine induces protective immunity of mice against enterotoxigenic Escherichia coli lethal challenge

Enterotoxigenic Escherichia coli (ETEC) is a global primary pathogenic bacterium causing diarrhoea in human and a wide variety of neonatal animals. Lactococcus lactis as non-pathogenic and food-grade lactic acid bacteria has already been explored as a vector for mucosal vaccine. Here, the current study was undertaken to evaluate the live recombinant L. lactis (rL. lactis) vaccine expressing the trivalent enterotoxin protein STa-LTB-STb and the F5 fimbrial antigen (SLS-F5) with OmpH of Yersinia enterocolitica in protection against ETEC. Western blot confirmed the expression of fusion protein SLS-F5-OmpH in nisin-controlled expression (NICE) system. Mice orally immunized with rL. lactis-SLS-F5-OmpH were observed to produce high levels of mucosal SIgA and serum IgG antibodies, while also inducing increases in the production of CD4⁺ and CD8⁺ T cells, lymphocyte proliferation, and secretion of cytokines. Moreover, orally immunized mice produced complete protection after ETEC challenge. The above results suggested that rL. lactis-SLS-F5-OmpH has the potential as a candidate for oral vaccine against ETEC.

Breastfeeding and Mortality Under 2 Years of Age in Sub-Saharan Africa

BACKGROUND

Several studies have investigated the association of breastfeeding status with offspring mortality in Africa, but most studies were from one center only or had limited statistical power to draw robust conclusions.

METHODS

Data came from 75 nationally representative cross-sectional Demographic and Health Surveys in 35 countries in sub-Saharan Africa conducted between 2000 and 2016. Our study relied on 217 112 individuals aged 4 days to 23 months for breastfeeding pattern analysis, 161 322 individuals aged 6 to 23 months for breastfeeding history analysis, and 104 427 individuals aged 12 to 23 months for breastfeeding duration analysis.

RESULTS

Compared with children aged 4 days to 23 months exclusively breastfed in the first 3 days of life, those not breastfed had a high risk of mortality at <2 years of age (odds ratio [OR] = 13.45; 95% confidence interval [CI] = 11.43-15.83). Young children who were predominantly breastfed or partially breastfed had moderately increased risk of mortality at <2 years of age (OR = 1.11, 95% CI = 1.03-1.21 for predominant pattern; OR = 1.12, 95% CI = 0.99-1.27 for partial pattern). Compared with children aged 6 to 23 months who were breastfed within the first 6 months of life, those not breastfed had a high risk of mortality (OR = 5.65; 95% CI = 4.27-7.47). Compared with children aged 12 to 23 months who were breastfed for ≥6 months, those who were breastfed for shorter periods had a higher risk of mortality (OR = 2.78, 95% CI = 1.45-5.32 for duration of <3 months; OR = 5.28, 95% CI = 3.24-8.61 for those who were not breastfed).

CONCLUSIONS

Our findings support exclusive breastfeeding during the first 6 months of life and continued breastfeeding up to 2 years of age recommended by the World Health Organization for reducing mortality of children <2 years old in sub-Saharan Africa.

A specific gene-microbe interaction drives the development of Crohn's disease-like colitis in mice

Bacterial dysbiosis is associated with Crohn's disease (CD), a chronic intestinal inflammatory disorder thought to result from an abnormal immune response against intestinal bacteria in genetically susceptible individuals. However, it is unclear whether dysbiosis is a cause or consequence of intestinal inflammation and whether overall dysbiosis or specific bacteria trigger the disease. Here, we show that the combined deficiency of NOD2 and phagocyte NADPH oxidase, two CD susceptibility genes, triggers early-onset spontaneous T_H1-type intestinal inflammation in mice with the pathological hallmarks of CD. Disease was induced by Mucispirillum schaedleri, a Gram-negative mucus-dwelling anaerobe. NOD2 and CYBB deficiencies led to marked accumulation of Mucispirillum, which was associated with impaired neutrophil recruitment and killing of the bacterium by luminal neutrophils. Maternal immunoglobulins against Mucispirillum protected mutant mice from disease during breastfeeding. Our results indicate that a specific intestinal microbe triggers CD-like disease in the presence of impaired clearance of the bacterium by innate immunity.