Breast milk-mediated transfer of an antigen induces tolerance and protection from allergic asthma

Understanding the burden of food allergy among urban and rural school children from north India

Background

There is paucity of reliable epidemiological data regarding the burden of food allergy in most developing countries, including India.

Objective

To provide current estimates of the prevalence and distribution of food allergy among urban and rural school children aged 6-14 years in Delhi and the National Capital Region (NCR) of Khekra in India.

Methods

A cross-sectional study was conducted from January 2022 to February 2023 to enroll school children, 6-14 years, from select urban and rural schools in Delhi and NCR. A questionnaire consisting of questions focused on household environment, early life factors, and pediatric food allergy characteristics was administered by a trained medical researcher to collect parent-proxy data. Univariate statistics were used to describe frequencies, percentages, and 95% confidence intervals for survey items.

Results

The estimated prevalence of parent-reported food allergy was 0.8% (95% CI: 0.4-1.5; urban: 0.4%, 95% CI: 0.1-1.1; rural: 1.7%, 95% CI: 0.7-3.5). Fruits such as mango (0.3%, 95% CI: 0.1-0.9), strawberry (0.1%, 95% CI: 0.0-0.7), orange (0.1%, 95% CI: 0.0-0.7), and custard apple (0.1%, 95% CI: 0.0-0.7) were reported only by urban children, while rural children reported yogurt (0.6%, 95% CI: 0.1-1.8) and wheat (0.3%, 95% CI: 0.0-1.3). Both groups reported brinjal (also known as eggplant) and banana, 0.1% (95% CI: 0.0-0.7) of urban and 0.3% (95% CI: 0.0-1.3) of rural, respectively. Overall, commonly reported clinical symptoms were diarrhea and/or vomiting (100%, 95% CI: 76.2-100), abdominal pain (88.9%, 95% CI: 58.6-98.8), and rash/itchy skin (66.7%, 95% CI: 34.8-89.6). Among children with parent reported food allergy, 66.7% (95% CI: 34.8-89.6) of food allergies were physician diagnosed, of which 33.3% were diagnosed via history alone (95% CI:7.7-71.4) while 66.7% (95% CI: 28.6-92.3) were confirmed via skin prick test and/or blood test.

Conclusion

The overall prevalence of food allergy is very low in Delhi and Khekra, India. Future work should focus on elucidating the complex interplay of early-life, environmental, genetic, and lifestyle factors to understand the reasons for India's low food allergy burden and improve epidemiological clues to prevention for the nations with higher disease burden.

TGFβ prevents IgE-mediated allergic disease by restraining T follicular helper 2 differentiation

Allergic diseases are common, affecting more than 20% of the population. Genetic variants in the TGFβ pathway are strongly associated with atopy. To interrogate the mechanisms underlying this association, we examined patients and mice with Loeys-Dietz syndrome (LDS) who harbor missense mutations in the kinase domain of TGFΒR1/2. We demonstrate that LDS mutations lead to reduced TGFβ signaling and elevated total and allergen-specific IgE, despite the presence of wild-type T regulatory cells in a chimera model. Germinal center activity was enhanced in LDS and characterized by a selective increase in type 2 follicular helper T cells (TFH2). Expression of Pik3cg was increased in LDS TFH cells and associated with reduced levels of the transcriptional repressor SnoN. PI3Kγ/mTOR signaling in LDS naïve CD4+ T cells was elevated after T cell receptor cross-linking, and pharmacologic inhibition of PI3Kγ or mTOR prevented exaggerated TFH2 and antigen-specific IgE responses after oral antigen exposure in an adoptive transfer model. Naïve CD4+ T cells from nonsyndromic allergic individuals also displayed decreased TGFβ signaling, suggesting that our mechanistic discoveries may be broadly relevant to allergic patients in general. Thus, TGFβ plays a conserved, T cell-intrinsic, and nonredundant role in restraining TFH2 development via the PI3Kγ/mTOR pathway and thereby protects against allergic disease.

Association of cesarean section with asthma in children/adolescents: a systematic review and meta-analysis based on cohort studies

BACKGROUND

Whether cesarean section (CS) is a risk factor for asthma in offspring is controversial. The purpose of this study was to investigate the association between CS and asthma in children/adolescents.

METHODS

Pubmed, Embase, Web of Science, and Cochrane Library electronic databases were searched for cohort studies on the relationship between mode of delivery and asthma in children/adolescents up to February 2023. Birth via CS was considered an exposure factor. Asthma incidence was taken as a result.

RESULTS

Thirty-five cohort studies (thirteen prospective and twenty-two retrospective cohort studies) were included. The results showed that the incidence of asthma was higher in CS offspring (odds ratio (OR) = 1.18, P < 0.001) than in the vaginal delivery (VD) group. Partial subgroup analyses showed a higher incidence of asthma in female offspring born via CS (OR = 1.26, P < 0.001) compared with the VD group, while there was no difference in males (OR = 1.07, P = 0.325). Asthma incidence was higher in CS offspring than in the VD group in Europe (OR = 1.20, P < 0.001), North America (OR = 1.15, P < 0.001), and Oceania (OR = 1.06, P = 0.008). This trend was not found in the Asian population (OR = 1.17, P = 0.102). The incidence of atopic asthma was higher in offspring born via CS (OR = 1.14, P < 0.001) compared to the VD group. The CS group had a higher incidence of persistent asthma, but the difference did not reach statistical significance (OR = 1.15, P = 0.063).

CONCLUSION

In this meta-analysis, CS may be a risk factor for asthma in offspring children/adolescents compared with VD. The relationship between CS and asthma was influenced by sex and region.

Biomarkers associated with persistence and severity of IgE-mediated food allergies: a systematic review

OBJECTIVE

The prevalence of food allergies (FA) has increased worldwide over the last few decades. Milk, eggs, and peanuts are among the most common allergens and can cause anaphylaxis. Therefore, we aimed to identify biomarkers that could predict the persistence and/or severity of IgE-mediated allergies to milk, eggs, and peanuts via a systematic review.

METHODS

This systematic review proceeded according to a protocol registered in the International Prospective Register of Systematic Reviews. Two independent authors extracted studies of interest from PubMed, SciELO, EMBASE, Scopus, and Ebsco databases and assessed their quality using the Newcastle-Ottawa Scale.

RESULTS

We selected 14 articles describing 1,398 patients. Among eight identified biomarkers, total IgE, specific IgE (sIgE), and IgG4 were the most often cited biomarkers of persistent allergies to milk, eggs, and peanuts. Skin prick tests, endpoint tests, and sIgE cutoff levels may predict positive responses to challenges with these foods. The basophil activation test is a biomarker for the severity and/or threshold of allergic reactions to milk and peanuts.

CONCLUSION

Only a few publications identified possible prognostic indicators of the persistence or severity of FA and outcomes of oral food challenges, indicating that more accessible biomarkers are needed to determine the likelihood of having a severe food allergic reaction.

The therapeutic age of the neonatal Fc receptor

IgGs are essential soluble components of the adaptive immune response that evolved to protect the body from infection. Compared with other immunoglobulins, the role of IgGs is distinguished and enhanced by their high circulating levels, long half-life and ability to transfer from mother to offspring, properties that are conferred by interactions with neonatal Fc receptor (FcRn). FcRn binds to the Fc portion of IgGs in a pH-dependent manner and protects them from intracellular degradation. It also allows their transport across polarized cells that separate tissue compartments, such as the endothelium and epithelium. Further, it is becoming apparent that FcRn functions to potentiate cellular immune responses when IgGs, bound to their antigens, form IgG immune complexes. Besides the protective role of IgG, IgG autoantibodies are associated with numerous pathological conditions. As such, FcRn blockade is a novel and effective strategy to reduce circulating levels of pathogenic IgG autoantibodies and curtail IgG-mediated diseases, with several FcRn-blocking strategies on the path to therapeutic use. Here, we describe the current state of knowledge of FcRn-IgG immunobiology, with an emphasis on the functional and pathological aspects, and an overview of FcRn-targeted therapy development.

The Protective Role of Exosome-Derived MicroRNAs and Proteins from Human Breast Milk against Infectious Agents

Human breast milk (HBM)-derived exosomes contain various biological and immunological components. However, comprehensive immune-related and antimicrobial factor analysis requires transcriptomic, proteomic, and multiple databases for functional analyses, and has yet to be conducted. Therefore, we isolated and confirmed HBM-derived exosomes by detecting specific markers and examining their morphology using western blot and transmission electron microscopy. Moreover, we implemented small RNA sequencing and liquid chromatography-mass spectrometry to investigate substances within the HBM-derived exosomes and their roles in combating pathogenic effects, identifying 208 miRNAs and 377 proteins associated with immunological pathways and diseases. Integrated omics analyses identified a connection between the exosomal substances and microbial infections. In addition, gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that HBM-derived exosomal miRNA and proteins influence immune-related functions and pathogenic infections. Finally, protein-protein interaction analysis identified three primary proteins (ICAM1, TLR2, and FN1) associated with microbial infections mediating pro-inflammation, controlling infection, and facilitating microbial elimination. Our findings determine that HBM-derived exosomes modulate the immune system and could offer therapeutic strategies for regulating pathogenic microbial infection.

Regulatory Role of microRNA of Milk Exosomes in Mastitis of Dairy Cows

The aim of this study was to compare the cargos of miRNA in exosomes isolated from the milk of healthy (H) cows, cows at risk of mastitis (ARM), and cows with subclinical mastitis (SCM). Based on the number of somatic cells and the percentage of polymorphonuclear cells, 10 cows were assigned to group H, 11 to group ARM, and 11 to group SCM. After isolating exosomes in milk by isoelectric precipitation and ultracentrifugation, the extracted RNA was sequenced to 50 bp long single reads, and these were mapped against Btau_5.0.1. The resulting 225 miRNAs were uploaded to the miRNet suite, and target genes for Bos taurus were identified based on the miRTarBase and miRanda databases. The list of differentially expressed target genes resulting from the comparisons of the three groups was enriched using the Function Explorer of the Kyoto Encyclopedia of Genes and Genomes. A total of 38, 18, and 12 miRNAs were differentially expressed (DE, p < 0.05) in the comparisons of H vs. ARM, ARM vs. SCM, and H vs. SCM, respectively. Only 1 DE miRNA was shared among the three groups (bta-mir-221), 1 DE miRNA in the H vs. SCM comparison, 9 DE miRNAs in the ARM vs. SCM comparison, and 21 DE miRNAs in the H vs. ARM comparison. A comparison of the enriched pathways of target genes from the H, SCM, and ARM samples showed that 19 pathways were differentially expressed in the three groups, while 56 were expressed in the H vs. SCM comparison and 57 in the H vs. ARM comparison. Analyzing milk exosome miRNA cargos can be considered as a promising approach to study the complex molecular machinery set in motion in response to mastitis in dairy cows.

Antibiotic Treatment during Gestation Enhances Susceptibility to Mycobacterium tuberculosis in Offspring

Whether antibiotic treatment during gestation impacts T cell immunity to vaccination in offspring is unexplored. Dams treated with polymyxin B (PMB) during gestation (Mg) displayed altered microbial communities prior to delivery compared to control dams (Mc). Differences in microbiota were also evident in pups born to polymyxin B-treated dams (Pg) compared to control pups (Pc). When pups were immunized with Bacille Calmette-Guerin (BCG), we observed no difference in TB10.4-specific T cells between Pc and Pg 4 weeks postimmunization. Significantly fewer splenic CD4 T cells from BCG-vaccinated Pg produced interleukin-2 (IL-2) upon stimulation, suggesting a possible functional deficiency. There was no difference in purified protein derivative (PPD)-specific IgG between Pc and Pg at this time point. However, when infected with Mycobacterium tuberculosis, Pg displayed significantly higher bacterial burden in the lung than Pc. Our results show that maternal PMB treatment during gestation may not impact splenic antigen-specific T cell responses following BCG vaccination but alters susceptibility to M. tuberculosis in offspring. IMPORTANCE The composition of the pioneer microbiota that colonize the infant gut are determined by the mother. Polymyxin B-induced changes in the maternal microbiota during pregnancy impact the offspring gut microbiota but not vaccine-specific CD4 T cell response. However, when infected with Mycobacterium tuberculosis, offspring born to mothers with an altered gut microbiota are susceptible to infection compared to those born to mothers not exposed to antibiotics.

Perinatal exposure to foodborne inorganic nanoparticles: A role in the susceptibility to food allergy?

Food allergy (FA) is an inappropriate immune response against dietary antigens. Various environmental factors during perinatal life may alter the establishment of intestinal homeostasis, thereby predisposing individuals to the development of such immune-related diseases. Among these factors, recent studies have emphasized the chronic dietary exposure of the mother to foodborne inorganic nanoparticles (NP) such as nano-sized silicon dioxide (SiO₂), titanium dioxide (TiO₂) or silver (Ag). Indeed, there is growing evidence that these inorganic agents, used as food additives in various products, as processing aids during food manufacturing or in food contact materials, can cross the placental barrier and reach the developing fetus. Excretion in milk is also suggested, hence continuing to expose the neonate during a critical window of susceptibility. Due to their immunotoxical and biocidal properties, such exposure may disrupt the host-intestinal microbiota's beneficial exchanges and may interfere with intestinal barrier and gut-associated immune system development in fetuses then the neonates. The resulting dysregulated intestinal homeostasis in the infant may significantly impede the induction of oral tolerance, a crucial process of immune unresponsiveness to food antigens. The current review focuses on the possible impacts of perinatal exposure to foodborne NP during pregnancy and early life on the susceptibility to developing FA.

Babies, Bugs, and Barriers: Dietary Modulation of Intestinal Barrier Function in Early Life

The intestinal barrier is essential in early life to prevent infection, inflammation, and food allergies. It consists of microbiota, a mucus layer, an epithelial layer, and the immune system. Microbial metabolites, the mucus, antimicrobial peptides, and secretory immunoglobulin A (sIgA) protect the intestinal mucosa against infection. The complex interplay between these functionalities of the intestinal barrier is crucial in early life by supporting homeostasis, development of the intestinal immune system, and long-term gut health. Exclusive breastfeeding is highly recommended during the first 6 months. When breastfeeding is not possible, milk-based infant formulas are the only safe alternative. Breast milk contains many bioactive components that help to establish the intestinal microbiota and influence the development of the intestinal epithelium and the immune system. Importantly, breastfeeding lowers the risk for intestinal and respiratory tract infections. Here we review all aspects of intestinal barrier function and the nutritional components that impact its functionality in early life, such as micronutrients, bioactive milk proteins, milk lipids, and human milk oligosaccharides. These components are present in breast milk and can be added to milk-based infant formulas to support gut health and immunity. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Breastfeeding: Maternally Transferred Allergens in Breast Milk: Protective or Sensitizing?

According to a thorough literature search, the following allergen sources have been associated with allergy symptoms in the exclusively breastfed child: hen's egg, cow's milk, peanut, trout. Subsequently, several studies use the advantage of molecular allergology and investigate the potential transfer of single allergens into breastmilk. This is shown for caseins, whey proteins, gliadin, ovalbumin, ovomucoid, the peanut allergens Ara h 2 and Ara h 6, as well as the inhalant allergens Der p 1 and Blo t 5. It is still a matter of debate whether or not food allergens transferred via breastfeeding to the baby promote allergic sensitization or induce tolerance and via which mechanisms they may shift the immune response to the one or other side. Noteworthy, some breastfed children are described to be sensitized to foods before being exposed to solid foods, and this exposure may have occurred through breastmilk. In the light of these findings the investigation of food allergens transferred from the mother's diet into breastmilk and their impact on sensitization or allergy prevention remains a current topic in research. This review describes breastmilk in its composition and provides data on the identification of food allergens therein including human and mouse studies.

House Dust Mite Exposure through Human Milk and Dust: What Matters for Child Allergy Risk?

Allergies are major noncommunicable diseases associated with significant morbidity, reduced quality of life, and high healthcare costs. Despite decades of research, it is still unknown if early-life exposure to indoor allergens plays a role in the development of IgE-mediated allergy and asthma. The objective of this study is to contribute to the identification of early-life risk factors for developing allergy. We addressed whether two different sources of house dust mite Der p 1 allergen exposure during early life, i.e., human milk and dust, have different relationships with IgE levels and asthma outcomes in children. We performed longitudinal analyses in 249 mother−child pairs using data from the PIAMA birth cohort. Asthma symptoms and serum total and specific IgE levels in children were available for the first 16 years of life. Der p 1 levels were measured in human milk and dust samples from infant mattresses. We observed that infant exposure to Der p 1 through human milk was associated with an increased risk of having high levels of serum IgE (top tertile > 150 kU/mL) in childhood as compared to infants exposed to human milk with undetectable Der p 1 [adjusted OR (95% CI) 1.83 (1.05−3.20) p = 0.0294]. The Der p 1 content in infant mattress dust was not associated with increased IgE levels in childhood. The risk of asthma and Der p 1 sensitization was neither associated with Der p 1 in human milk nor with Der p 1 in dust. In conclusion, high levels of IgE in childhood were associated with Der p 1 exposure through human milk but not exposure from mattress dust. This observation suggests that human milk is a source of Der p 1 exposure that is relevant to allergy development and fosters the need for research on the determinants of Der p 1 levels in human milk.

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.

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.

Hallmarks of the human intestinal microbiome on liver maturation and function

As one of the most metabolically complex systems in the body, the liver ensures multi-organ homeostasis and ultimately sustains life. Nevertheless, during early postnatal development, the liver is highly immature and takes about 2 years to acquire and develop almost all of its functions. Different events occurring at the environmental and cellular levels are thought to mediate hepatic maturation and function postnatally. The crosstalk between the liver, the gut and its microbiome has been well appreciated in the context of liver disease, but recent evidence suggests that the latter could also be critical for hepatic function under physiological conditions. The gut-liver crosstalk is thought to be mediated by a rich repertoire of microbial metabolites that can participate in a myriad of biological processes in hepatic sinusoids, from energy metabolism to tissue regeneration. Studies on germ-free animals have revealed the gut microbiome as a critical contributor in early hepatic programming, and this influence extends throughout life, mediating liver function and body homeostasis. In this seminar, we describe the microbial molecules that have a known effect on the liver and discuss how the gut microbiome and the liver evolve throughout life. We also provide insights on current and future strategies to target the gut microbiome in the context of hepatology research.

Next generation strategies to recover immunological tolerance in celiac disease

Celiac disease (CD) is an autoimmune disease that occurs in genetically predisposed individuals following the ingestion of gluten. Its prevalence is rising worldwide. A gluten-free (GF) diet is mandatory for the management of CD. However, several issues persist regarding the nutritional quality of GF products. Importantly, deep knowledge about the pathogenic mechanisms in CD highlights the central role of CD4⁺ T cell-mediated immunity in CD. Furthermore, intestinal T regulatory cells are functional in CD, but cytokines such as IL-15, produced under inflammatory conditions, hamper their activity. This paves the way for the development of immunomodulatory strategies to the GF diet. From this perspective, microbiological approaches were considered able to modulate the gluten-specific immune response. Interestingly, gliadin peptide-based immunotherapy to abolish the inflammatory CD4⁺T cell-mediated response has been explored in CD patients. Furthermore, different biotechnological approaches based on the use of chemically/enzymatically modified gluten molecules have been proved effective in different models of CD. However, the choice of the right age in infants to introduce the antigen and thus induce tolerance still remains an important issue to solve. Addressing all these points should help to design an effective intervention strategy for preventing CD.

Analysing the protection from respiratory tract infections and allergic diseases early in life by human milk components: the PRIMA birth cohort

Background

Many studies support the protective effect of breastfeeding on respiratory tract infections. Although infant formulas have been developed to provide adequate nutritional solutions, many components in human milk contributing to the protection of newborns and aiding immune development still need to be identified. In this paper we present the methodology of the “Protecting against Respiratory tract lnfections through human Milk Analysis” (PRIMA) cohort, which is an observational, prospective and multi-centre birth cohort aiming to identify novel functions of components in human milk that are protective against respiratory tract infections and allergic diseases early in life.

Methods

For the PRIMA human milk cohort we aim to recruit 1000 mother–child pairs in the first month postpartum. At one week, one, three, and six months after birth, fresh human milk samples will be collected and processed. In order to identify protective components, the level of pathogen specific antibodies, T cell composition, Human milk oligosaccharides, as well as extracellular vesicles (EVs) will be analysed, in the milk samples in relation to clinical data which are collected using two-weekly parental questionnaires. The primary outcome of this study is the number of parent-reported medically attended respiratory infections. Secondary outcomes that will be measured are physician diagnosed (respiratory) infections and allergies during the first year of life.

Discussion

The PRIMA human milk cohort will be a large prospective healthy birth cohort in which we will use an integrated, multidisciplinary approach to identify the longitudinal effect human milk components that play a role in preventing (respiratory) infections and allergies during the first year of life. Ultimately, we believe that this study will provide novel insights into immunomodulatory components in human milk. This may allow for optimizing formula feeding for all non-breastfed infants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07107-w.

Asthma, allergy and vitamin E: Current and future perspectives

Asthma and allergic disease result from interactions of environmental exposures and genetics. Vitamin E is one environmental factor that can modify development of allergy early in life and modify responses to allergen after allergen sensitization. Seemingly varied outcomes from vitamin E are consistent with the differential functions of the isoforms of vitamin E. Mechanistic studies demonstrate that the vitamin E isoforms α-tocopherol and γ-tocopherol have opposite functions in regulation of allergic inflammation and development of allergic disease, with α-tocopherol having anti-inflammatory functions and γ-tocopherol having pro-inflammatory functions in allergy and asthma. Moreover, global differences in prevalence of asthma by country may be a result, at least in part, of differences in consumption of these two isoforms of tocopherols. It is critical in clinical and animal studies that measurements of the isoforms of tocopherols be determined in vehicles for the treatments, and in the plasma and/or tissues before and after intervention. As allergic inflammation is modifiable by tocopherol isoforms, differential regulation by tocopherol isoforms provide a foundation for development of interventions to improve lung function in disease and raise the possibility of early life dietary interventions to limit the development of lung disease.

Immunomodulatory and anti-inflammatory effects of N-acetylcysteine in ovalbumin-sensitized rats

Background

Pro-inflammatory cytokines such as interleukin-5 (IL-5) and tumor necrosis factor-alpha (TNF-α) as well as immunoglobulin-E (IgE) appear to play a role in asthma. N-acetylcysteine (NAC), an antioxidant, might have clinical benefits in asthma prevention. The possible preventive effects of NAC against experimentally induced asthma in rats are investigated. The rats were allocated into five groups: a normal control, asthma control, a standard dexamethasone (DEXA, 1 mg/kg, orally) group, and two NAC groups (300 and 500 mg/kg, orally, respectively). Ovalbumin (OVA) sensitization was used to trigger asthma, which was then followed by an intra-nasal challenge. Test gents were administrated for 14 days before the challenge and during the three challenge days (20, 21, and 22). The tidal volume (TV) and peak expiratory flow rate (PEFR) as respiratory functions were determined. The pro-inflammatory cytokines as IL-5 and TNF-α were evaluated in lung homogenate. Serum IgE and absolute eosinophil count (AEC) in bronchoalveolar lavage fluid (BALF) were measured. In addition, the oxidative markers in lung tissue and nitrosative marker in BALF were assessed; finally, lungs were isolated for histopathological study.

Results

NAC restored lung functions, inhibited the asthma-dependent increase in TNF-α, IL-5, IgE, AEC, nitric oxide, and malondialdehyde levels. NAC further re-established lung glutathione content and superoxide dismutase activity, resulting in milder overall lung pathology.

Conclusions

Experimental bronchial asthma may be protected by NAC. The anti-asthmatic potential of NAC may be explained by its suppressant influence on IgE antibody formation, pro-inflammatory cytokines production, eosinophil infiltration, and oxidative stress.

Breastmilk, Stool, and Meconium: Bacterial Communities in South Africa

Human milk optimizes gut microbial richness and diversity, and is critical for proper immune development. Research has shown differing microbial composition based on geographic location, providing evidence that diverse biospecimen data is needed when studying human bacterial communities. Yet, limited research describes human milk and infant gut microbial communities in Africa. Our study uses breastmilk, stool, and meconium samples from a South African birth cohort to describe the microbial diversity, identify distinct taxonomic units, and determine correlations between bacterial abundance in breastmilk and stool samples. Mother-infant dyads (N = 20) were identified from a longitudinal birth cohort in the Vhembe district of Limpopo Province, South Africa. Breastmilk, meconium, and stool samples were analyzed using 16S ribosomal RNA sequencing of the V4-V5 gene region using the MiSeq platform for identification and relative quantification of bacterial taxa. A non-metric multidimensional scaling using Bray-Curtis distances of sample Z-scores showed that meconium, stool, and breastmilk microbial communities are distinct with varying genus. Breastmilk was mostly comprised of Streptococcus, Staphylococcus, Veillonella, and Corynebacterium. Stool samples showed the highest levels of Bifidobacterium, Faecalibacterium, Bacteroides, and Streptococcus. Alpha diversity measures found that stool samples have the highest Shannon index score compared to breastmilk and meconium. The abundance of Bifidobacterium (r = 0.57), Blautia (r = 0.59), and Haemophilus (r = 0.69) was correlated (p < 0.1) between breastmilk and stool samples. Despite the importance of breastmilk in seeding the infant gut microbiome, we found evidence of distinct bacterial communities between breastmilk and stool samples from South African mother-infant dyads.

Oxytocin Regulates the Expression of Selected Colostrum-derived microRNAs

OBJECTIVE

The highly expressed microRNAs (miRNAs) in milk are known as beneficial miRNAs, such as mir148a-3p, which is related to immune system development and disease prevention. There is a need to study their expression and secretion regulatory mechanism in breast milk. We hypothesize that oxytocin can be involved in the regulation of expression and secretion of milk-derived miRNAs.

METHODS

Initially, oxytocin's effect on miRNA expression in human mammary cells was analyzed. Secondly, the expression of selected miRNAs in mothers' colostrum treated or not with oxytocin before, during, or after labor was compared. MiRNA expression was analyzed by quantitative real-time PCR.

RESULTS

The expression of miR-148a was significantly upregulated, and miR-320 downregulated in oxytocin-treated mammary cells as well as their secreted extracellular vesicles to the media, compared with untreated cells. MiR-148a was found to be upregulated, and miR-320 was downregulated in the human colostrum of exogenous oxytocin-treated mothers. Moreover, miR-320 was highly expressed compared with miR-148a in the colostrum of mothers that did not receive exogenous oxytocin. In contrast, in the milk of mothers who received exogenous oxytocin, the expression of miRNA-148-3p was highly expressed compared with miR-320.

CONCLUSIONS

This study shows that oxytocin modulates the expression of main milk-derived miRNAs. Our findings provide a novel insight into oxytocin's role in milk composition by regulating miRNA expression. Our results implicate that oxytocin increases miRNA expression in mammary epithelial cells and human milk, affecting human milk composition and may contribute to further infant health.

Characteristics of Exogenous Allergen in Breast Milk and Their Impact on Oral Tolerance Induction

Food allergy is a common health problem in childhood since its prevalence was estimated to range from 6. 5 to 24.6% in European countries. Recently, a lot of research has focused on the impact of breastfeeding on oral tolerance induction. Since it was found that breast milk contains immunologically active food antigens, it would be very helpful to clarify the factors of antigen shedding that promotes oral tolerance. This narrative review aimed to summarize the latest evidence from experimental and human studies regarding allergen characteristics in human milk that may influence oral tolerance induction. A literature search in PubMed, MEDLINE, and Google Scholar was conducted. The diet of the mother was found to have a direct impact on allergen amount in the breastmilk, while antigens had different kinetics in human milk between women and depending on the antigen. The mode of antigen consumption, such as the cooking of an antigen, may also affect the allergenicity of the antigen in human milk. The dose of the antigen in human milk is in the range of nanograms per milliliter; however, it was found to have a tolerogenic effect. Furthermore, the presence of antigen-specific immunoglobulins, forming immune complexes with antigens, was found more tolerogenic compared to free allergens in experimental studies, and this is related to the immune status of the mother. While examining available data, this review highlights gaps in knowledge regarding allergen characteristics that may influence oral tolerance.

The Exposome Approach in Allergies and Lung Diseases: Is It Time to Define a Preconception Exposome?

Emerging research suggests environmental exposures before conception may adversely affect allergies and lung diseases in future generations. Most studies are limited as they have focused on single exposures, not considering that these diseases have a multifactorial origin in which environmental and lifestyle factors are likely to interact. Traditional exposure assessment methods fail to capture the interactions among environmental exposures and their impact on fundamental biological processes, as well as individual and temporal factors. A valid estimation of exposure preconception is difficult since the human reproductive cycle spans decades and the access to germ cells is limited. The exposome is defined as the cumulative measure of external exposures on an organism (external exposome), and the associated biological responses (endogenous exposome) throughout the lifespan, from conception and onwards. An exposome approach implies a targeted or agnostic analysis of the concurrent and temporal multiple exposures, and may, together with recent technological advances, improve the assessment of the environmental contributors to health and disease. This review describes the current knowledge on preconception environmental exposures as related to respiratory health outcomes in offspring. We discuss the usefulness and feasibility of using an exposome approach in this research, advocating for the preconception exposure window to become included in the exposome concept.

Inherent maternal type 2 immunity: Consequences for maternal and offspring health

An inherent elevation in type 2 immunity is a feature of maternal and offspring immune systems. This has diverse implications for maternal and offspring biology including influencing success of pregnancy, offspring immune development and maternal and offspring ability to control infection and diseases such as allergies. In this review we provide a broad insight into how this immunological feature of pregnancy and early life impacts both maternal and offspring biology. We also suggest how understanding of this axis of immune influence is and may be utilised to improve maternal and offspring health.

Allergic diseases in infancy: I - Epidemiology and current interpretation

Objective

Among non-communicable diseases, the prevalence of allergic diseases has increased significantly in the new millennium. The increase of allergic diseases is linked to the changing environment of infants.

Methods

This narrative review summarizes the discussions and conclusions from the 8^th Human Milk Workshop. Information from the fields of pediatrics, epidemiology, biology, microbiology, and immunology are summarized to establish a framework describing potential avenues for the prevention of allergic diseases in the future.

Results

Several environmental circumstances are linked to the development of allergic diseases. While cesarean section is increasing the risk of allergies, early childhood exposure to a farm environment has a protective effect. From their analysis, nutritive and non-nutritive factors influencing the allergy risk in later life have been identified. The effect of breastfeeding on food allergy development is non-univocal. Human milk components including immunoglobulins, cytokines, and prebiotics have been indicated as important for allergy prevention.

Conclusion

Many factors linked to the western lifestyle have been associated with the development of allergic diseases. This suggests several theories that may serve as a basis for new protective interventions. While it is indubitable that mother's milk protects from infectious diseases, its role in the prevention of allergic diseases is to be elucidated.

Traditional Farming Lifestyle in Old Older Mennonites Modulates Human Milk Composition

Background

In addition to farming exposures in childhood, maternal farming exposures provide strong protection against allergic disease in their children; however, the effect of farming lifestyle on human milk (HM) composition is unknown.

Objective

This study aims to characterize the maternal immune effects of Old Order Mennonite (OOM) traditional farming lifestyle when compared with Rochester (ROC) families at higher risk for asthma and allergic diseases using HM as a proxy.

Methods

HM samples collected at median 2 months of lactation from 52 OOM and 29 ROC mothers were assayed for IgA₁ and IgA₂ antibodies, cytokines, endotoxin, HM oligosaccharides (HMOs), and targeted fatty acid (FA) metabolites. Development of early childhood atopic diseases in children by 3 years of age was assessed. In addition to group comparisons, systems level network analysis was performed to identify communities of multiple HM factors in ROC and OOM lifestyle.

Results

HM contains IgA₁ and IgA₂ antibodies broadly recognizing food, inhalant, and bacterial antigens. OOM HM has significantly higher levels of IgA to peanut, ovalbumin, dust mites, and Streptococcus equii as well TGF-β2, and IFN-λ3. A strong correlation occurred between maternal antibiotic use and levels of several HMOs. Path-based analysis of HMOs shows lower activity in the path involving lactoneohexaose (LNH) in the OOM as well as higher levels of lacto-N-neotetraose (LNnT) and two long-chain FAs C-18OH (stearic acid) and C-23OH (tricosanoic acid) compared with Rochester HM. OOM and Rochester milk formed five different clusters, e.g., butyrate production was associated with Prevotellaceae, Veillonellaceae, and Micrococcaceae cluster. Development of atopic disease in early childhood was more common in Rochester and associated with lower levels of total IgA, IgA₂ to dust mite, as well as of TSLP.

Conclusion

Traditional, agrarian lifestyle, and antibiotic use are strong regulators of maternally derived immune and metabolic factors, which may have downstream implications for postnatal developmental programming of infant's gut microbiome and immune system.

"Ways in which the neonatal Fc-receptor is involved in autoimmunity"

Since the neonatal IgG Fc receptor (FcRn) was discovered, its role has evolved from immunoglobulin recycling and biodistribution to antigen presentation and immune complex routing, bringing it to the center of both humoral and cellular immune responses. FcRn is thus involved in the pathophysiology of immune-related diseases such as cancer, infection, and autoimmune disorders. This review focuses on the role of FcRn in autoimmunity, based on the available data from both animal models and human studies. The knowledge concerning ways in which FcRn is involved in autoimmune response has led to the development of inhibitors for the treatment of autoimmune diseases, also described here. Up to date, the literature remains scarce, shedding light on the need for further studies to fully understand the various pathophysiological roles of this unique receptor.

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FcRn is an intracellular receptor with a key role in IgG and immune complex management.

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FcRn-targeting therapies are a promising way of treatment in antibodies mediated diseases.

Oral tolerance as antigen-specific immunotherapy

Oral tolerance is a physiological phenomenon described more than a century ago as a suppressive immune response to antigens that gain access to the body by the oral route. It is a robust and long-lasting event with local and systemic effects in which the generation of mucosally induced regulatory T cells (iTreg) plays an essential role. The idea of using oral tolerance to inhibit autoimmune and allergic diseases by oral administration of target antigens was an important development that was successfully tested in 1980s. Since then, several studies have shown that feeding specific antigens can be used to prevent and control chronic inflammatory diseases in both animal models and clinically. Therefore, oral tolerance can be classified as an antigen-specific form of oral immunotherapy (OIT). In the light of novel findings on mechanisms, sites of induction and factors affecting oral tolerance, this review will focus on specific characteristics of oral tolerance induction and how they impact in its therapeutic application.

Comparative proteome profiling in exosomes derived from porcine colostrum versus mature milk reveals distinct functional proteomes

Exosomes are membranous vesicles of endocytic origin, recently been considered as major players in cell-cell communication. Milk is highly complex, and diverse biocomponents provide adequate nutrition, transfer immunity, and promote adequate neonate development. Milk exosomes are suggested to have a key role in these processes, yet to be further explored, and the alteration of the exosomes' cargo in different stages of lactation stages is important for understanding the factors relevant in nursing and also for improving milk replacer products both for humans and animals. We isolated exosomes from porcine milk in different lactation stages and analyzed their content using a TMT-based high-resolution quantitative proteomic approach. Exosomes were isolated using ultracentrifugation coupled with size exclusion chromatography to enrich milk-derived exosomes in samples obtained at day 0, 7, and 14 after parturition, and characterized by nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. Quantitative proteomics analysis revealed different proteome profiles for colostrum exosomes and milk exosomes. The functional analysis highlighted pathways related to the regulation of homeostasis to be upregulated in colostrum exosomes, and pathways such as endothelial cell development and lipid metabolism to be upregulated in mature milk exosomes. This study endorses the importance of exosomes as active biocomponents of milk and provides knowledge for future studies exploring their role in the regulation of immunity and growth of the newborn. SIGNIFICANCE: The identified functional proteome and protein-protein interaction networks identified in our study help to elucidate the role of milk exosomes in different lactation periods. The results generated herein are of relevance for the basic understanding of their impact on the infant's development but also for bringing forward the manufacturing of milk replacers.

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.

Preconceptional Immunization Can Modulate Offspring Intrathymic IL-17-Producing γδT Cells with Epigenetic Implications Mediated by microRNAs

The mechanisms through which maternal immunization can modulate offspring thymic maturation of lymphocytes are not fully understood. Here, we aimed to evaluate whether maternal OVA-immunization can inhibit the maturation of IL-17-producing γδT cells in offspring thymus, and if this mechanism has epigenetic implications mediated by microRNAs (miRNAs) expression. Wild-type (WT) C57BL/6 females were immunized with OVA in Alum or Alum alone and were mated with normal WT males. Evaluating their offspring thymus at 3 or 20 days old (d.o.), we observed that maternal OVA immunization could inhibit the thymic frequency of offspring CD27- and IL-17+ γδT cells at the neonatal and until 20 days old. Furthermore, we evaluated the expression of function-related γ and δ variable γδTCR chains (Vγ1, Vγ2, Vγ3, Vδ4, and Vδ6.3), observing that maternal OVA-immunization inhibits Vγ2 chains expression. The small RNAs (sRNAs), particularly miRNAs, and messenger RNAs (mRNA) expression profiles by pools of thymus tissue samples (from 9 to 11 mice) from offspring OVA-immunized or Alum-immunized mothers were analyzed via Illumina sequencing platform and bioinformatics approaches. Using a fold change >4, our results showed that seven miRNAs (mmu-miR-126a-3p, 101a-3p, 744-3p,142-5p, 15a-5p, 532-5p, and 98-5p) were differentially expressed between both groups. Ten target genes were predicted to interact with the seven selected miRNAs. There were no enriched categories of gene ontology functional annotation and pathway enrichment analysis for the target genes. Interestingly, four of the identified miRNAs (mmu-miR-15a, mmu-miR-101 mmu-miR-126, and mmu-miR-142) are related to IL-17 production. Our data is of significance because we demonstrate that maternal immunization can modulate offspring thymic maturation of IL-17-producing γδT cells possibly by an epigenetic mechanism mediated by miRNAs.

Allergen Exposure in Murine Neonates Promoted the Development of Asthmatic Lungs

We previously demonstrated that fetal allergen exposure caused T-helper 2 (Th2) cell sensitization. Although neonates are immunologically more mature than fetuses, asthmatic lungs were reportedly mitigated by neonatal allergen administration, mechanically referring to regulatory T-cells and TGF-β signaling but lacking the immunological profiles after neonatal exposure. To reappraise the immunological outcome of neonatal allergen exposure, we injected adjuvant-free ovalbumin intraperitoneally into 2-day-old BALB/c neonates, followed by aerosolized ovalbumin inhalation in adulthood. Mice were examined for the immunological profiles specifically after neonatal exposures, lung function and histology (hematoxylin-eosin or periodic acid Schiff staining), and gene expressions of intrapulmonary cytokines (IL-4, IL-5, IL-13 and IFN-γ) and chemokines (CCL17, CCL22, CCL11 and CCL24). Neonatal ovalbumin exposure triggered Th2-skewed sensitization and ovalbumin-specific IgE production. Subsequent ovalbumin inhalation in adulthood boosted Th2 immunity and caused asthmatic lungs with structural and functional alterations of airways. Gender difference mainly involved airway hyperresponsiveness and resistance with greater female susceptibility to methacholine bronchospastic stimulation. In lungs, heightened chemoattractant gene expressions were only granted to neonatally ovalbumin-sensitized mice with aerosolized ovalbumin stress in adulthood, and paralleled by upregulated Th2 cytokine genes. Thus, aeroallergen stress in atopic individuals might upregulate the expression of intrapulmonary chemoattractants to recruit Th2 cells and eosinophils into the lungs, pathogenically linked to asthma development. Conclusively, murine neonates were sensitive to allergen exposures. Exposure events during neonatal stages were crucial to asthma predisposition in later life. These findings from a murine model point to allergen avoidance in neonatal life, possibly even very early in utero, as the best prospect of primary asthma prevention.

Breastfeeding and Allergic Diseases: What's New?

Asthma and other allergic disorders, such as atopic dermatitis and food allergies, are common chronic health problems in childhood. The rapid rise in the prevalence of these conditions registered over the last few decades has stressed the need to identify the modifiable risk factors associated with the development of these diseases. Breast milk, recognized as the gold standard for healthy growth and development of the newborn, is one of the major factors associated with a lower incidence of allergic and infectious diseases in childhood and young adulthood. Although the underlying mechanisms for these effects are not well understood, breastfeeding leads to immune system maturation. In this narrative review, we summarize existing evidence on breastfeeding and human milk composition in relation to allergic disease prevention or development.

Supplementation of Bovine Colostrum in Inflammatory Bowel Disease: Benefits and Contraindications

Inflammatory bowel disease (IBD) is a group of chronic relapsing disorders whose etiology has not been fully explained. Therefore, available therapeutic approaches for IBD patients are still insufficient. Current treatment strategies are targeted to immune system dysfunctions, often associated with alternations in the microbiota, which contribute to the development of chronic intestinal inflammation. Therapeutics include anti-inflammatory drugs such as aminosalicylates and corticosteroids, immunosuppressive agents, antibiotics, and biological agents such as infliximab and vedolizumab. Auxiliary therapies involve a balanced and personalized diet, healthy lifestyle, avoiding stress, as well as dietary supplements. In this review, we discuss the use of bovine colostrum (BC) as a therapeutic agent, including its advantages and contraindications. We summarize our knowledge on well-researched BC constituents and their effects on the gastrointestinal tract as evidenced in in vitro and in vivo studies.

Breast Milk: A Source of Functional Compounds with Potential Application in Nutrition and Therapy

Breast milk is an unbeatable food that covers all the nutritional requirements of an infant in its different stages of growth up to six months after birth. In addition, breastfeeding benefits both maternal and child health. Increasing knowledge has been acquired regarding the composition of breast milk. Epidemiological studies and epigenetics allow us to understand the possible lifelong effects of breastfeeding. In this review we have compiled some of the components with clear functional activity that are present in human milk and the processes through which they promote infant development and maturation as well as modulate immunity. Milk fat globule membrane, proteins, oligosaccharides, growth factors, milk exosomes, or microorganisms are functional components to use in infant formulas, any other food products, nutritional supplements, nutraceuticals, or even for the development of new clinical therapies. The clinical evaluation of these compounds and their commercial exploitation are limited by the difficulty of isolating and producing them on an adequate scale. In this work we focus on the compounds produced using milk components from other species such as bovine, transgenic cattle capable of expressing components of human breast milk or microbial culture engineering.

In Translation: FcRn across the Therapeutic Spectrum

As an essential modulator of IgG disposition, the neonatal Fc receptor (FcRn) governs the pharmacokinetics and functions many therapeutic modalities. In this review, we thoroughly reexamine the hitherto elucidated biological and thermodynamic properties of FcRn to provide context for our assessment of more recent advances, which covers antigen-binding fragment (Fab) determinants of FcRn affinity, transgenic preclinical models, and FcRn targeting as an immune-complex (IC)-clearing strategy. We further comment on therapeutic antibodies authorized for treating SARS-CoV-2 (bamlanivimab, casirivimab, and imdevimab) and evaluate their potential to saturate FcRn-mediated recycling. Finally, we discuss modeling and simulation studies that probe the quantitative relationship between in vivo IgG persistence and in vitro FcRn binding, emphasizing the importance of endosomal transit parameters.

Immunologic components in human milk and allergic diseases with focus on food allergy

Human milk contains a wide range of immunomodulatory factors, including immunoglobulins, human milk oligosaccharides, cytokines, microbiome, innate factors and food antigens. Maternal diet can influence the content of human milk as it is well-established that dietary antigens can be secreted in human milk after maternal consumption, but whether these dietary antigens promote tolerance or sensitization in the infant is a subject of debate. This review summarizes the current literature on these immunologically active factors in human milk, including the microbiome, innate factors, and maternal diet-derived dietary antigens in the context of development of allergic diseases, with the focus on food allergy.

Perinatal and Early-Life Nutrition, Epigenetics, and Allergy

Epidemiological studies have shown a dramatic increase in the incidence and the prevalence of allergic diseases over the last several decades. Environmental triggers including risk factors (e.g., pollution), the loss of rural living conditions (e.g., farming conditions), and nutritional status (e.g., maternal, breastfeeding) are considered major contributors to this increase. The influences of these environmental factors are thought to be mediated by epigenetic mechanisms which are heritable, reversible, and biologically relevant biochemical modifications of the chromatin carrying the genetic information without changing the nucleotide sequence of the genome. An important feature characterizing epigenetically-mediated processes is the existence of a time frame where the induced effects are the strongest and therefore most crucial. This period between conception, pregnancy, and the first years of life (e.g., first 1000 days) is considered the optimal time for environmental factors, such as nutrition, to exert their beneficial epigenetic effects. In the current review, we discussed the impact of the exposure to bacteria, viruses, parasites, fungal components, microbiome metabolites, and specific nutritional components (e.g., polyunsaturated fatty acids (PUFA), vitamins, plant- and animal-derived microRNAs, breast milk) on the epigenetic patterns related to allergic manifestations. We gave insight into the epigenetic signature of bioactive milk components and the effects of specific nutrition on neonatal T cell development. Several lines of evidence suggest that atypical metabolic reprogramming induced by extrinsic factors such as allergens, viruses, pollutants, diet, or microbiome might drive cellular metabolic dysfunctions and defective immune responses in allergic disease. Therefore, we described the current knowledge on the relationship between immunometabolism and allergy mediated by epigenetic mechanisms. The knowledge as presented will give insight into epigenetic changes and the potential of maternal and post-natal nutrition on the development of allergic disease.

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

Mice Pups Breastfed by Foster Mothers Whose Breast Milk Contains Plasmodium falciparum Recombinant SE36 Antigen Develop Specific Antibodies

Intranasal instillation of SE36, a malaria vaccine candidate antigen, in lactating BALB/c female mice resulted in the appearance of the antigen in breast milk as demonstrated by sandwich ELISA and Western blot. Pups born of immunologically naive mice and breastfed on lactating foster mothers exposed intranasally to SE36 developed IgG anti-SE36 antibodies. These data demonstrate that maternal immunization in mice by this route in lactating mothers can result in active immunization of offspring via ingestion of breast milk containing antigen. If confirmed in a nonhuman primate model and in human subjects, this strategy might be transformative for vaccination against malaria and other infant killer infectious diseases.

Vagal-α7nAChR signaling attenuates allergic asthma responses and facilitates asthma tolerance by regulating inflammatory group 2 innate lymphoid cells

Disorders of immune tolerance may lead to allergic asthma. Group 2 innate lymphoid cells (ILC2s) and inflammatory ILC2s (iILC2s) are key players in asthma. The vagus nerve innervating the airways releases acetylcholine or neuropeptides (i.e. calcitonin gene-related peptide) via pulmonary C-fibers (PCFs), which could regulate ILC2 activity upon binding the α7 nicotinic acetylcholine receptor (α7nAChR, coded by Chrna7) or neuropeptide receptors. Whether and how α7nAChR and PCFs regulate asthma and the formation of asthma tolerance via ILC2s or iILC2s are poorly understood. We used vagotomized, PCF degeneration and Chrna7 knockout mice to investigate ovalbumin (OVA)-induced asthma and oral OVA feeding-induced asthma tolerance. Our results revealed that vagotomy could generally suppress lung ILC2s and iILC2s, which mitigated allergic asthma responses but disrupted asthmatic tolerance. Removal of neuropeptides by PCF degeneration also reduced lung ILC2s and iILC2s, attenuating asthma responses, but did not affect asthma tolerance. In comparison, deletion of Chrna7 increased resident ILC2s and trafficking iILC2s in the lung, worsened allergic inflammation and disrupted oral tolerance. Mechanistically, deletion of Chrna7 in asthma-tolerant conditions upregulated T helper 2 cytokine- (Il4, Il13 and Il25) and sphingosine-1-phosphate (S1P)-related genes (S1pr1 and Sphk1). Blockade of S1P reduced iILC2 recruitment into asthmatic lungs. Our work is the first to demonstrate that vagal-α7nAChR signaling engaging with iILC2s and S1P not only alleviates asthma but also facilitates asthma tolerance. These findings may provide a novel therapeutic target for attenuating asthma by enhancing asthmatic tolerance.

The Microbiota of the Human Mammary Ecosystem

Human milk contains a dynamic and complex site-specific microbiome, which is not assembled in an aleatory way, formed by organized microbial consortia and networks. Presence of some genera, such as Staphylococcus, Streptococcus, Corynebacterium, Cutibacterium (formerly known as Propionibacterium), Lactobacillus, Lactococcus and Bifidobacterium, has been detected by both culture-dependent and culture-independent approaches. DNA from some gut-associated strict anaerobes has also been repeatedly found and some studies have revealed the presence of cells and/or nucleic acids from viruses, archaea, fungi and protozoa in human milk. Colostrum and milk microbes are transmitted to the infant and, therefore, they are among the first colonizers of the human gut. Still, the significance of human milk microbes in infant gut colonization remains an open question. Clinical studies trying to elucidate the question are confounded by the profound impact of non-microbial human milk components to intestinal microecology. Modifications in the microbiota of human milk may have biological consequences for infant colonization, metabolism, immune and neuroendocrine development, and for mammary health. However, the factors driving differences in the composition of the human milk microbiome remain poorly known. In addition to colostrum and milk, breast tissue in lactating and non-lactating women may also contain a microbiota, with implications in the pathogenesis of breast cancer and in some of the adverse outcomes associated with breast implants. This and other open issues, such as the origin of the human milk microbiome, and the current limitations and future prospects are addressed in this review.

Altered Gut Microbiome and Environmental Factors Associated with Development of Eczema in Hong Kong Infants: A 4-Month Pilot Study

Eczema is a multifactorial skin disease that affects 20% of children worldwide and has a complex relationship with microbial, nutritional, parental and environmental factors. In this study, we investigated the potential association of eczema with the gut microbiome and environmental factors. One hundred and fifty-two newborn subjects and their mothers were recruited within 10 days postnatally at the Prince of Wales Hospital in Hong Kong, China and asked to complete questionnaires on allergies, maternal diet and environmental assessment at enrolment. Then, the participants were classified as with or without eczema at four months after birth based on the Comprehensive Early Childhood Allergy Questionnaire (CECAQ) and SCORing Atopic Dermatitis (SCORAD) index (n = 48, with 24 in each group). Stool samples were collected from both groups at the same time. Microbial DNA was extracted from each stool sample, and 16S rRNA sequencing was performed to analyze the gut microbiome profiles of the subjects. Our results indicated that the abundance of Bifidobacterium was significantly higher in the eczema group than in the control group (p = 0.04). A multivariable logistic regression analysis was conducted, and the results showed that the father’s education level and maternal intake of cereal products and nutritional supplements during pregnancy were associated with the development of eczema (p = 0.008, 0.032 and 0.015, respectively). In conclusion, this study provided preliminary information about the potential risk factors of eczema development in Hong Kong infants in support of a future full study.

The Potential of IgG to Induce Murine and Human Thymic Maturation of IL-10+ B Cells (B10) Revealed in a Pilot Study

Regulatory B (B10) cells can control several inflammatory diseases, including allergies; however, the origin of peripheral B10 cells is not fully understood, and the involvement of primary lymphoid organs (PLOs) as a primary site of maturation is not known. Here, using a murine model of allergy inhibition mediated by maternal immunization with ovalbumin (OVA), we aimed to evaluate whether B10 cells can mature in the thymus and whether IgG can mediate this process. Female mice were immunized with OVA, and offspring thymus, bone marrow, spleen, lung, and serum samples were evaluated at different times and after passive transfer of purified IgG or thymocytes. A translational approach was implemented using human nonatopic thymus samples, nonatopic peripheral blood mononuclear cells (PBMCs), and IgG from atopic or nonatopic individuals. Based on the expression of CD1d on B cells during maturation stages, we suggest that B10 cells can also mature in the murine thymus. Murine thymic B10 cells can be induced in vitro and in vivo by IgG and be detected in the spleen and lungs in response to an allergen challenge. Like IgG from atopic individuals, human IgG from nonatopic individuals can induce B10 cells in the infant thymus and adult PBMCs. Our observations suggest that B10 cells may mature in the thymus and that this mechanism may be mediated by IgG in both humans and mice. These observations may support the future development of IgG-based immunoregulatory therapeutic strategies.

Administration of Extensive Hydrolysates From Caseins and Lactobacillus rhamnosus GG Probiotic Does Not Prevent Cow's Milk Proteins Allergy in a Mouse Model

Background

Early nutrition may influence the development of food allergies later in life. In the absence of breastfeeding, hydrolysates from cow’s milk proteins (CMP) were indicated as a prevention strategy in at risk infants, but their proof of effectiveness in clinical and pre-clinical studies is still insufficient. Thanks to a validated mouse model, we then assessed specific and nonspecific preventive effects of administration of extensive hydrolysates from caseins (eHC) on the development of food allergy to CMP. The additional nonspecific effect of the probiotic Lactobacillus GG (LGG), commonly used in infant formula, was also assessed.

Methods

Groups of young BALB/cByJ female mice were pretreated by repeated gavage either with PBS (control mice), or with PBS solution containing non-hydrolyzed milk protein isolate (MPI), eHC or eHC+LGG (eq. of 10 mg of protein/gavage). All mice were then experimentally sensitized to CMP by gavage with whole CM mixed with the Th2 mucosal adjuvant Cholera toxin. All mice were further chronically exposed to cow’s milk. A group of mice was kept naïve. Sensitization to both caseins and to the non-related whey protein β-lactoglobulin (BLG) was evaluated by measuring specific antibodies in plasma and specific ex vivo Th2/Th1/Th17 cytokine secretion. Elicitation of the allergic reaction was assessed by measuring mMCP1 in plasma obtained after oral food challenge (OFC) with CMP. Th/Treg cell frequencies in gut-associated lymphoid tissue and spleen were analyzed by flow cytometry at the end of the protocol. Robust statistical procedure combining non-supervised and supervised multivariate analyses and univariate analyses, was conducted to reveal any effect of the pretreatments.

Results

PBS pretreated mice were efficiently sensitized and demonstrated elicitation of allergic reaction after OFC, whereas mice pretreated with MPI were durably protected from allergy to CMP. eHC+/-LGG pretreatments had no protective effect on sensitization to casein (specific) or BLG (non-specific), nor on CMP-induced allergic reactions. Surprisingly, eHC+LGG mice demonstrated significantly enhanced humoral and cellular immune responses after sensitization with CMP. Only some subtle changes were evidenced by flow cytometry.

Conclusion

Neither specific nor nonspecific preventive effects of administration of casein-derived peptides on the development of CMP food allergy were evidenced in our experimental setup. Further studies should be conducted to delineate the mechanisms involved in the immunostimulatory potential of LGG and to clarify its significance in clinical use.

iNKT cells with high PLZF expression are recruited into the lung via CCL21-CCR7 signaling to facilitate the development of asthma tolerance in mice

Establishment of immune tolerance is crucial to protect humans against asthma. Promyelocytic leukemia zinc finger (PLZF) is an emerging suppressor of inflammatory responses. CCL21-CCR7 signaling mediates tolerance development. However, whether PLZF and CCL21-CCR7 are required for the development of asthma tolerance is unknown. Here, we found that Zbtb16 (coding PLZF) and Ccl21 were upregulated in OVA-induced asthma tolerance (OT) lungs by RNA-seq. PLZF physically interacted with GATA3 and its expression was higher in GATA3⁺ Th2 cells and ILC2s in OT lungs. Zbtb16-knockdown in lymphocytes promoted the differentiation of CD3e⁺ CD4⁺ T cells, particularly those producing IL-4 and IL-5. Moreover, iNKT cells with high expression of PLZF were recruited into the lungs via draining lymph nodes during tolerance. Blockade of CCL21-CCR7 signaling in OT mice decreased the PLZF⁺  cell population, abolished CCR7-induced PLZF⁺ iNKT recruitment to the lungs, enhanced Th2responses and exacerbated lung pathology. In OT mice, respiratory syncytial virus (RSV) infection impeded PLZF⁺  cell and CCR7⁺ PLZF⁺ iNKT cellrecruitment to the lungs and increased airway resistance. Collectively, these results indicate that PLZF could interact with GATA3 and restrain differentiation of IL-4- and IL-5-producing T cells, iNKT cells with high PLZF expression are recruited to the lungs via CCL21-CCR7 signaling to facilitate the development of asthma tolerance.

Preconception helminth infection alters offspring microbiota and immune subsets in a mouse model

Both maternal microbiota and helminth infection may alter offspring immunity but the relationship between these is underexplored. We hypothesized that maternal helminth exposure prior to pregnancy has lasting consequences on offspring intestinal microbiota and consequent immunity. Female BALB/c adult mice were infected with 500L3 Nippostrongylus brasiliensis (N brasiliensis). Infection was cleared by ivermectin treatment, and mice were mated 3 weeks post-infection (NbM). Control mice were not infected but were exposed to ivermectin (NvM). We analysed maternal gut microbiota during pregnancy, breastmilk microbiota and offspring faecal microbiota and immunity 2 weeks after delivery. During pregnancy, NbM (Mothers previously infected with Nippostrongylus brasiliensis) displayed significantly altered stool bacterial communities (R2  = .242; P = .001), with increased abundance of Enterococcaceae versus NvM (Naive mothers). Similarly, we observed a profound impact on breastmilk microbiota in NbM vs NvM. Moreover, NbM pups showed significantly altered gut microbial communities at 14 days of age versus those born to NvM with increased relative abundance of Coriobacteriaceae and Micrococcaceae. These changes were associated with alterations in pup immunity including increased frequencies and numbers of activated CD4 T cells (CD4 + CD44hi) in NbM offspring spleens. Taken together, we show that preconception helminth infections impact offspring immunity possibly through alteration of maternal and offspring microbiota.

Prevention of Allergy to a Major Cow's Milk Allergen by Breastfeeding in Mice Depends on Maternal Immune Status and Oral Exposure During Lactation

Background: The high incidence of food allergy in childhood points to the need of elucidating early life factors dictating allergy susceptibility. Here, we aim to address in a mouse model how the exposure to a major cow's milk allergen through breastmilk of mothers with different immune status influences food allergy outcome in offspring.

Methods: BALB/cJ future dams were either kept naïve, or sensitized through the oral route using cholera toxin (“orally sensitized”) or through the i.p. route using alum (“i.p. sensitized”), or rendered fully tolerant (oral gavage without any adjuvant) to bovine β-lactoglobulin (BLG). After mating with naïve males and delivery, mothers were orally exposed or not to BLG during the whole lactation. Then, eight groups of lactating mothers were considered: naïve, i.p. sensitized, orally sensitized, or tolerant, each exposed or not during lactation. In order to specifically address breastmilk effects on their allergy susceptibility, pups from naïve-synchronized mothers were cross-fostered by the different groups of treated dams and lactating mothers at delivery. In some experiments, mothers kept their own pups to address a possible in utero effect. BLG antigen, BLG-specific antibodies, and BLG-immune complexes were measured in breastmilk from the different lactating mother groups. Allergic sensitization was monitored in 5-weeks old female offspring (n = 7–8/group of lactating mothers) by determining BLG-specific antibodies in plasma and splenocytes cytokine secretion after i.p. injections of BLG/alum. Allergic reaction to oral BLG challenge was evaluated by measuring mMCP1 in plasma.

Results: Offspring was protected from one allergic i.p. sensitization when nursed by i.p. sensitized mothers, independently of BLG exposure during lactation. Orally sensitized dams conferred protection in offspring solely when exposed to BLG during lactation, while naïve mothers did not provide any protection upon BLG exposure. The levels of protection correlated with the levels of BLG-specific antibodies and BLG-immune complex in breastmilk. There was a trend for decreased sensitization in offspring breastfed by tolerant and exposed mothers, which was not associated with transfer of specific antibodies through breastmilk. Protection provided by nursing by treated/exposed mothers was not persistent after a boost i.p. injection of the progeny and then did not protect them from an allergic reaction induced at this time point. No additional in utero effects were evidenced.

Conclusion: Our study demonstrates the strong potential of breastmilk to modulate immune response to a major cow's milk allergen in the progeny. It highlights the importance of maternal immune status and of her consumption of the allergen during lactation in dictating the outcomes in offspring. This opens perspectives where modulating maternal immune status might increase the chance of cow's milk allergy prevention in breastfed children.