Detection of major food allergens in amniotic fluid: initial allergenic encounter during pregnancy

Amniotic fluid modifies esophageal epithelium differentiation and inflammatory responses

The interplay between genetic and environmental factors during pregnancy can predispose to inflammatory diseases postnatally, including eosinophilic esophagitis (EoE), a chronic allergic disease triggered by food. Herein, we examined the effects of amniotic fluid (AF) on esophageal epithelial differentiation and responsiveness to proallergic stimuli. Multiplex analysis of AF revealed the expression of 66 cytokines, whereas five cytokines including IL-4 and thymic stromal lymphopoietin (TSLP) were not detected. Several proinflammatory cytokines including TNFα and IL-12 were highly expressed in the AF from women who underwent preterm birth, whereas EGF was the highest in term birth samples. Exposure of esophageal epithelial cells to AF resulted in transient phosphorylation of ERK1/2 and the transcription of early response genes, highlighting the direct impact of AF on esophageal epithelial cells. In a three-dimensional spheroid model, AF modified the esophageal epithelial differentiation program and enhanced the transcription of IL-13-target genes, including CCL26 and CAPN14, which encodes for a major genetic susceptibility locus for eosinophilic esophagitis. Notably, CAPN14 exhibited upregulation in spheroids exposed to preterm but not term AF following differentiation. Collectively, our findings call attention to the role of AF as a potential mediator of the intrauterine environment that influences subsequent esophageal disorders.NEW & NOTEWORTHY The interaction between amniotic fluid and the esophageal epithelium during pregnancy modifies esophageal epithelial differentiation and subsequent responsiveness to inflammatory stimuli, including interleukin 13 (IL-13). This interaction may predispose individuals to inflammatory conditions of the esophagus, such as eosinophilic esophagitis (EoE), in later stages of life.

Foetal gluten immunogenic peptides during pregnancy: a new determinant on the coeliac exposome

BACKGROUND

The increasing incidence of coeliac disease is leading to a growing interest in active search for associated factors, even the intrauterine and early life. The exposome approach to disease encompasses a life course perspective from conception onwards has recently been highlighted. Knowledge of early exposure to gluten immunogenic peptides (GIP) in utero could challenge the chronology of early prenatal tolerance or inflammation, rather than after the infant's solid diet after birth.

METHODS

We developed an accurate and specific immunoassay to detect GIP in amniotic fluid (AF) and studied their accumulates, excretion dynamics and foetal exposure resulting from AF swallowing. One hundred twenty-five pregnant women with different gluten diets and gestational ages were recruited.

RESULTS

GIP were detectable in AF from at least the 16th gestational week in gluten-consuming women. Although no significant differences in GIP levels were observed during gestation, amniotic GIP late pregnancy was not altered by maternal fasting, suggesting closed-loop entailing foetal swallowing of GIP-containing AF and subsequent excretion via the foetal kidneys.

CONCLUSIONS

The study shows evidence, for the first time, of the foetal exposure to gluten immunogenic peptides and establishes a positive correlation with maternal gluten intake. The results obtained point to a novel physiological concept as they describe a plausible closed-loop circuit entailing foetal swallowing of GIP contained in AF and its subsequent excretion through the foetal kidneys. The study adds important new information to understanding the coeliac exposome.

Prevention of IgE-Mediated Food Allergy: Emerging Strategies Through Maternal and Neonatal Interventions

Whereas the early introduction of highly allergenic foods has been shown to be effective at preventing the onset of food allergy (FA) in high-risk infants, sensitization to food antigens can occur prior to complementary food introduction, and thus, additional earlier FA prevention strategies are urgently needed. Currently, aside from early introduction of peanut and egg, no therapies are strongly recommended by international professional allergy societies for the primary prevention of FA. This review focuses on maternal- and neonatal-directed interventions that are being actively investigated and developed, including maternal dietary factors and supplementation, specific elimination diets, breastfeeding, cow's milk formula supplementation, microbiome manipulations, bacterial lysate therapy, and skin barrier therapies. Evaluating how these factors and various prenatal/early life environmental exposures may impact the development of FA is crucial for accurately counseling caregivers in the prevention of FA.

Prenatal Factors in the Development of Allergic Diseases

Allergic diseases are showing increasing prevalence in Western societies. They are characterized by a heightened reactivity towards otherwise harmless environmental stimuli. Allergic diseases showing a wide range of severity of symptoms have a significant impact on the quality of life of affected individuals. This study aims to highlight the mechanisms that induce these reactions, how they progress, and which prenatal factors influence their development. Most frequently, the reaction is mediated by immunoglobulin E (IgE) produced by B cells, which binds to the surface of mast cells and basophils and triggers an inflammatory response. The antibody response is triggered by a shift in T-cell immune response. The symptoms often start in early childhood with eczema or atopic dermatitis and progress to allergic asthma in adolescence. An important determinant of allergic diseases seems to be parental, especially maternal history of allergy. Around 30% of children of allergic mothers develop allergic sensitization in childhood. Genes involved in the regulation of the epithelial barrier function and the T-cell response were found to affect the predisposition to developing allergic disorders. Cord blood IgE was found to be a promising predictor of allergic disease development. Fetal B cells produce IgE starting at the 20th gestation week. These fetal B cells could be sensitized together with mast cells by maternal IgE and IgE-allergen complexes crossing the placental barrier via the low-affinity IgE receptor. Various factors were found to facilitate these sensitizations, including pesticides, drugs, exposure to cigarette smoke and maternal uncontrolled asthma. Prenatal exposure to microbial infections and maternal IgG appeared to play a role in the regulation of T-cell response, indicating a protective effect against allergy development. Additional preventive factors were dietary intake of vitamin D and omega 3 fatty acids as well as decreased maternal IgE levels. The effect of exposure to food allergens during pregnancy was inconclusive, with studies having found both sensitizing and protective effects. In conclusion, prenatal factors including genetics, epigenetics and fetal environmental factors have an important role in the development of allergic disorders in later life. Children with a genetic predisposition are at risk when exposed to cigarette smoke as well as increased maternal IgE in the prenatal period. Maternal diet during pregnancy and immunization against certain allergens could help in the prevention of allergy in predisposed children.

Food Allergens: When Friends Become Foes-Caveats and Opportunities for Oral Immunotherapy Based on Deactivation Methods

Food allergies represent a serious health concern and, since the 1990s, they have risen gradually in high-income countries. Unfortunately, the problem is complex because genetic, epigenetic, and environmental factors may be collectively involved. Prevention and diagnoses have not yet evolved into efficacious therapies. Identification and control of allergens present in edible substances hold promise for multi-purpose biomedical approaches, including oral immunotherapy. This review highlights recent studies and methods to modify the otherwise innocuous native proteins in most subjects, and how oral treatments targeting immune responses could help cancel out the potential risks in hypersensitive individuals, especially children. We have focused on some physical methods that can easily be conducted, along with chemo-enzymatic modifications of allergens by means of peptides and phytochemicals in particular. The latter, accessible from naturally-occurring substances, provide an added value to hypoallergenic matrices employing vegetal wastes, a point where food chemistry meets sustainable goals as well.

A review of current evidence on food allergies during pregnancy

Food allergy is the reaction of the immune system of the body that occurs after consuming specific foods. During specific physiological ages of pregnancy, women are more prone to different allergic reactions and mostly these reactions may prolong and have long-term effects. The hypersensitivity of different types of allergens is mainly linked with the adversity of reactions. The chances of suffering food allergies in women are greater than in men; women are usually more prone to get allergic to some foods during their specific physiological age of pregnancy. Food allergies are more common in pregnant women as every fifth pregnant woman is affected by some kind of allergy. The specific reasons and evidence of the causes of these food allergies during pregnancies have yet to be explored. A pregnant woman should take a balanced diet and avoid consuming known allergic foods to minimize the risk and complications. This review aimed to broaden the knowledge on food allergies during pregnancies, their onset in the babies, and to make it easy for pregnant women to cope with the complications caused by these food allergies. It also aimed to figure out the certain food that might be responsible for the onset of allergies in women during pregnancy and the effect of these allergies on their babies.

Beyond allergic progression: From molecules to microbes as barrier modulators in the gut-lung axis functionality

The "epithelial barrier hypothesis" states that a barrier dysfunction can result in allergy development due to tolerance breakdown. This barrier alteration may come from the direct contact of epithelial and immune cells with the allergens, and indirectly, through deleterious effects caused by environmental changes triggered by industrialization, pollution, and changes in the lifestyle. Apart from their protective role, epithelial cells can respond to external factors secreting IL-25 IL-33, and TSLP, provoking the activation of ILC2 cells and a Th2-biased response. Several environmental agents that influence epithelial barrier function, such as allergenic proteases, food additives or certain xenobiotics are reviewed in this paper. In addition, dietary factors that influence the allergenic response in a positive or negative way will be also described here. Finally, we discuss how the gut microbiota, its composition, and microbe-derived metabolites, such as short-chain fatty acids, alter not only the gut but also the integrity of distant epithelial barriers, focusing this review on the gut-lung axis.

Predictors and biomarkers of food allergy and sensitization in early childhood

OBJECTIVE

To review existing literature on the early risk factors for and biomarkers of food allergy (FA) and food sensitization (FS) and highlight opportunities for future research that will further the understanding of FA pathogenesis in infancy and toddlerhood.

DATA SOURCES

PubMed search of English-language articles related to FA and atopic disease.

STUDY SELECTIONS

Human studies with outcomes related to FA, FS, and other atopic disease in childhood were selected and reviewed. Studies published after 2015 were prioritized.

RESULTS

The prevalence of FA has greatly increased in recent decades and is now a global public health concern. A complex network of early life risk factors has been associated with development of FA and FS in childhood. Food allergy has a genetic component, but recent evidence suggests that interactions between risk alleles and other environmental exposures are important for disease pathogenesis, potentially through epigenetic mechanisms. Lifestyle factors, such as delivery mode, antibiotic use, and pet exposure also influence FA risk, which may be through their effect on the early life gut microbiome. How these early life risk factors, along with route and timing of antigen exposure, collectively target the developing immune system remains an ongoing and important area of study.

CONCLUSION

The current body of evidence emphasizes the first 1000 days of life as a critical period for FA development. More observational studies and adequately powered clinical trials spanning early pregnancy through childhood are needed to identify novel biomarkers and risk factors that can predict susceptibility toward or protection against FA.

PrEggNut Study: protocol for a randomised controlled trial investigating the effect of a maternal diet rich in eggs and peanuts from <23 weeks' gestation during pregnancy to 4 months' lactation on infant IgE-mediated egg and peanut allergy outcomes

INTRODUCTION

Clinical studies supported by immunological data indicate early life intervention strategies to be promising in reducing the growing global burden of food allergies. The events that predispose to food allergy, including the induction of allergen-specific immune responses, appear to be initiated early in development. Early exposure to food allergens in utero and via breast milk is likely to be important in initiating oral tolerance. We aim to determine the effectiveness of higher maternal food allergen consumption during pregnancy and lactation on infant food allergy outcomes.

METHODS AND ANALYSIS

This is a multisite, parallel, two-arm (1:1 allocation), single-blinded (outcome assessors, statistical analyst and investigators), randomised controlled trial. Pregnant women (<23 weeks' gestation) whose (unborn) infants have at least two biological family members (mother, father or siblings) with medically diagnosed allergic disease are eligible to participate. After obtaining written informed consent, pregnant women are randomised to either a high egg and peanut diet (at least 6 eggs and 60 peanuts per week) or standard (low) egg and peanut diet (no more than 3 eggs and 30 peanuts per week). The women are asked to follow their allocated diet from <23 weeks' gestation to 4 months' lactation. The primary outcome is food challenge proven IgE-mediated egg and/or peanut allergy in the infants at 12 months of age. Key secondary outcomes include infant sensitisation to egg and/or peanut and infant eczema. Our target sample size is 2136 women. Analyses will be performed on an intention-to-treat basis according to a pre-specified statistical analysis plan.

ETHICS AND DISSEMINATION

Ethical approval has been granted from the Women's and Children's Health Network Human Research Ethics Committee (approval number HREC/18/WCHN/42). Trial results will be presented at scientific conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry ACTRN12618000937213.

Selectin Dependence of Allergic Skin Inflammation Is Diminished by Maternal Atopy

Allergic skin inflammation requires the influx of inflammatory cells into the skin. Extravasation of leukocytes into the skin requires interactions between endothelial selectins and their glycan ligands on the surface of leukocytes. Selectin-ligand formation requires the activity of several glycosyltransferases, including Fut7 In this report, we tested the importance of Fut7 for the development of allergic skin inflammation in the Stat6VT transgenic mouse model. We observed that Fut7 deficiency was protective but did not eliminate disease. Segregation of the data by gender of the parent that transmitted the Stat6VT transgene, but not by gender of the pups, which were analyzed for disease, revealed that the protective effects of Fut7 deficiency were significantly greater when dams were Stat6VT negative. In contrast, in mice from litters of Stat6VT+ dams, Fut7 deficiency resulted in only modest protection. These findings indicate that pups from atopic dams exhibit a greater propensity for allergic disease, similar to observations in humans, and that the effect of maternal atopy is due to enhanced selectin-independent mechanisms of leukocyte recruitment in their offspring. Together, these results demonstrate that Fut7 deficiency can be protective in a model of atopic dermatitis but that maternal atopy diminishes these protective effects, suggesting alternative pathways for leukocyte recruitment in the absence of Fut7 enzyme activity. These observations have implications for understanding how the environment in utero predisposes for the development of allergic disease.

Maternal Dietary Protein Patterns During Pregnancy and the Risk of Infant Eczema: A Cohort Study

Background: Previous studies have suggested that maternal dietary protein was associated with allergic diseases in offspring, but few studies have evaluated the influence of dietary protein patterns. This study aimed to explore the prospective association between maternal dietary protein patterns during pregnancy and the risk of infant eczema.

Methods: A total of 713 mother-child pairs from a prospective cohort in Guangzhou, China were recruited. Maternal dietary protein was estimated using a validated face-to-face food frequency questionnaire at 20–28 weeks' gestation from 2017 to 2018. Dietary protein patterns were calculated based on the sources of protein. The data of infant eczema was assessed at 6 months of age using the symptom questionnaire of eczema. Logistic regression was carried out to examine the associations between maternal dietary protein patterns and infant eczema.

Results: The cumulative incidence of infant eczema at 6 months of age was 51.19%. Mothers of infants with eczema consumed more protein from poultry source during pregnancy than mothers of infants without eczema, while no statistical differences were observed in maternal intakes of protein from cereals and tubers, vegetables, fruits, red meat, fish and seafood, eggs, dairy, soybean, and nuts and seeds. Four dietary protein patterns were identified and termed poultry, plant, dairy and eggs, and red meat and fish. The cumulative incidence of eczema was 61.2, 45.8, 48.0, 51.4% for these four patterns, respectively. Compared to the poultry dietary pattern, the plant pattern and the dairy and eggs pattern were associated with a reduced risk of infant eczema, and the adjusted odds ratios (95% confidence interval) were 0.572 (0.330–0.992), 0.478 (0.274–0.837), respectively. No such association was observed for the red meat and fish dietary protein pattern.

Conclusion: This is the first study that focused on the association between maternal dietary protein during pregnancy from a whole-diet perspective and infant eczema. Compared with the poultry dietary protein pattern, the maternal plant pattern and the dairy and eggs pattern during pregnancy were associated with a reduced risk of infant eczema.

An integrative medicine review of primary prevention of allergy in pediatrics

The prevalence of allergic disease has been rapidly increasing in the developed world for over fifty years. The prevention of allergic disease remains one of the most elusive topics in medicine. Integrative medicine emphasizes prevention of disease and utilizes many interventions to help modify long-term outcomes of health. Primary prevention refers to the arrest of manifestations of a disease before they present clinically. Preventing allergy is not simply about preventing sensitization, but also about developing tolerance. This narrative review article will discuss integrative medicine approaches that may help to prevent atopic disease in the pediatric population. It is organized chronologically to aid in counseling patients: 1) prevention during pregnancy and 2) prevention after birth. While research into allergy prevention is in its infancy, Integrative Medicine is well-suited to provide many insights into the prevention and mitigation of atopic disease.

Viable bacterial colonization is highly limited in the human intestine in utero

Mucosal immunity develops in the human fetal intestine by 11-14 weeks of gestation, yet whether viable microbes exist in utero and interact with the intestinal immune system is unknown. Bacteria-like morphology was identified in pockets of human fetal meconium at mid-gestation by scanning electron microscopy (n = 4), and a sparse bacterial signal was detected by 16S rRNA sequencing (n = 40 of 50) compared to environmental controls (n = 87). Eighteen taxa were enriched in fetal meconium, with Micrococcaceae (n = 9) and Lactobacillus (n = 6) the most abundant. Fetal intestines dominated by Micrococcaceae exhibited distinct patterns of T cell composition and epithelial transcription. Fetal Micrococcus luteus, isolated only in the presence of monocytes, grew on placental hormones, remained viable within antigen presenting cells, limited inflammation ex vivo and possessed genomic features linked with survival in the fetus. Thus, viable bacteria are highly limited in the fetal intestine at mid-gestation, although strains with immunomodulatory capacity are detected in subsets of specimens.

Food Allergy Insights: A Changing Landscape

The panorama of food allergies (FA) has changed profoundly in recent years. In light of recent advances in knowledge of pathogenetic mechanisms and a greater attention to the multifaceted range of possible clinical manifestations, there is a need for a critical review of past classifications. Changes in nutrition, environment and lifestyles around the world are modifying the global FA epidemiology and new FA phenotypes are also emerging. Furthermore, both biotechnological advances in this field and recent personalized therapies have improved the diagnostic and therapeutic approach to FA. Consequently, both the prevention and clinical management of FA are rapidly changing and new therapeutic strategies are emerging, even revolutionizing the current medical practice. Given the significant increase in the prevalence of FA in recent years, the objective of this review is to provide an updated and complete overview of current knowledge in its etiopathogenesis, diagnostics and therapy, useful not only for a better understanding of this frequent and complex pathology but also for practical guidance in its clinical management.

New Perspectives in Food Allergy

The improvement of the knowledge of the pathophysiological mechanisms underlying the tolerance and sensitization to food antigens has recently led to a radical change in the clinical approach to food allergies. Epidemiological studies show a global increase in the prevalence of food allergy all over the world and manifestations of food allergy appear increasingly frequent also in elderly subjects. Environmental and nutritional changes have partly changed the epidemiology of allergic reactions to foods and new food allergic syndromes have emerged in recent years. The deepening of the study of the intestinal microbiota has highlighted important mechanisms of immunological adaptation of the mucosal immune system to food antigens, leading to a revolution in the concept of immunological tolerance. As a consequence, new prevention models and innovative therapeutic strategies aimed at a personalized approach to the patient affected by food allergy are emerging. This review focuses on these new perspectives and their practical implications in the management of food allergy, providing an updated view of this complex pathology.

Influences of Maternal Factors Over Offspring Allergies and the Application for Food Allergy

The prevalence of food allergy has been steadily rising worldwide with the highest incidence noted among younger children, and increasingly recognized as a growing public concern. The first known ingestion of foods often causes allergic reaction, suggesting that sensitization of offspring with food allergens may occur during pregnancy and/or through breastfeeding. This creates a milieu that shapes the neonatal immune responses to these allergens. However, the effects of maternal allergen exposure and maternal sensitization with allergens on development of allergies in offspring remain controversial. This review discusses recent advances from human data in our understanding of how maternal factors, namely, food allergens, allergen-specific immunoglobulins, cytokines, genetics, and environmental factors transferred during pregnancy or breastfeeding influence offspring allergies and how such effects may be applicable to food allergy. Based on information obtained from mouse models of asthma and food allergy, the review also dissects the mechanisms by which maternal factors, including the impact of immune complexes, transforming growth factor-β, vitamin A, and regulatory T-cell responses, contribute to the induction of neonatal tolerance vs. development of allergic responses to maternally transferred allergens.

Trajectories of class-switching-related egg and cow's milk allergen-specific immunoglobulin isotype formation and its modification by eczema with low- and high-affinity immunoglobulin E during early infancy

INTRODUCTION

Allergen-specific immunoglobulin isotype formation associated with immunoglobulin class-switching during the lactation period is the immunological background for food allergy in infants. We analyzed the serial changes in the production of feeding type-related egg- and milk-specific immunoglobulin isotypes from birth to 6 months of age with or without eczema in 84 infants.

METHODS

Allergen-specific immunoglobulin G1 (IgG1), IgG2, IgG3, IgG4, IgA, and IgE levels of hen's egg and bovine milk were measured in cord blood and blood samples from infants at 2, 4, and 6 months of age by the densely carboxylated protein microarray.

RESULTS

Formula and mixed feeding were associated with a rapid increase in cow's milk allergen-specific immunoglobulins and feeding type-related significant differences in casein-specific immunoglobulin levels were detected. Breast and mixed feeding were associated with slow but significant increase in ovalbumin-specific IgG1 and IgE levels, but not other immunoglobulins. We found two different immunoglobulin isotype formation at 6 months of age with low- or high-affinity IgE against ovalbumin. One isotype formation pattern had relatively high ovalbumin-specific IgG1 levels, detectable IgG2, and low-affinity IgE, while the other had low ovalbumin-specific IgG1 levels, undetectable IgG2, and high levels of high-affinity IgE. The incidence of eczema was significantly higher in the latter pattern (84.6%), compared with the remaining infants (42.2%).

CONCLUSIONS

Feeding practice-related allergen sensitization and immunoglobulin isotype formation were identified during the lactation period. The development of eczema during the lactation period could potentially modify the immunoglobulin isotype formation with high levels of high-affinity IgE.

Childhood food allergies: An evolutionary mismatch hypothesis

For hominins living in the Paleolithic era, early food antigen exposures—in utero and throughout infancy—closely matched later exposures, and therefore immune system tolerance mechanisms evolved under the expectation of this condition being met. This predicts that the degree of mismatch between early and downstream food antigen exposures is a key variable underlying the development of childhood food allergies. Three historical periods are identified in which the degree of mismatch climbs from near zero to substantial, as we transition from one period to another. The first encompasses our long history as foragers; the second begins with the advent of farming and the third spans only the most recent two or three decades, and manifests from social changes driven largely by an explosion in access to information. Testable predictions are generated and evaluated in light of available evidence, and an approach for primary prevention of childhood food allergies is proposed.

Food allergy and atopic dermatitis: Prediction, progression, and prevention

The rising burden of allergic diseases in childhood requires a compelling need to identify individuals at risk for atopy very early in life or even predict the onset of food allergy and atopic dermatitis since pregnancy. The development and clinical phenotypes of atopic diseases in childhood depend on a complex interaction between genetic and environmental factors, such as allergen exposure, air pollution, and infections. Preventive strategies may include avoidance measures, diet supplements, and early complementary food introduction. Overall, the management of allergic diseases has been improving to date toward a patient's tailored approach. This review will cover the current understanding of risk factors, prediction, and management of food allergy and atopic dermatitis in childhood and discuss how these may contribute to the modification of the natural history of food allergy and atopic dermatitis.

Food allergy in EAACI journals (2016)

Over the last years we have observed considerable progress in the area of food allergy, particularly in children. This review article focusses on important contributions which have lately been published in the three journals of the European Academy of Allergy and Clinical Immunology. A better understanding of allergens as well as the mechanisms of sensitization and tolerance induction may hopefully lead to a more targeted management of food allergy in the near future.

Pregnancy modulates the allergen-induced cytokine production differently in allergic and non-allergic women

BACKGROUND

The immunological environment during pregnancy may differ between allergic and non-allergic women. This study investigates the effect of maternal allergy on the allergen-induced cytokine and chemokine levels and whether pregnancy modulates these immune responses differently in allergic and non-allergic women.

METHODS

The birch-, cat-, phytohemagglutinin- and tetanus toxoid-induced interferon-γ (IFN-γ), interleukin (IL)-4, IL-5, IL-10, IL-13, the T-helper 1 (Th1)-associated chemokine CXCL10 and the Th2-associated chemokine CCL17 levels were quantified in 20 women with allergic symptoms (sensitized, n = 13) and 36 women without allergic symptoms (non-sensitized, n = 30) at gestational weeks 10-12, 15-16, 25, 35 and 2 and 12 months post-partum.

RESULTS

Birch-, but not cat-induced, IL-5, IL-13 and CCL17 levels were increased during pregnancy as compared to post-partum in the sensitized women with allergic symptoms. In contrast, cat-, but not birch-induced, IL-5 and IL-13 levels were increased during pregnancy as compared to post-partum in the non-sensitized women without allergic symptoms. Furthermore, IFN-γ secretion was increased in the first and decreased in the second and third trimesters in response to birch and decreased in the third trimester in response to cat as compared to post-partum in the non-sensitized women without allergic symptoms. Increased allergen-induced IL-4, IL-5 and IL-13 levels were associated with allergic symptoms and sensitization.

CONCLUSIONS

Pregnancy had a clear effect on the allergen-induced IL-5, IL-13, CCL17, IFN-γ and CXCL10 production, with distinct enhanced Th2-responses to birch in the allergic group and to cat in the non-allergic group.

Preterm Birth Affects the Risk of Developing Immune-Mediated Diseases

Prematurity affects approximately 10% of all children, resulting in drastically altered antigen exposure due to premature confrontation with microbes, nutritional antigens, and other environmental factors. During the last trimester of pregnancy, the fetal immune system adapts to tolerate maternal and self-antigens, while also preparing for postnatal immune defense by acquiring passive immunity from the mother. Since the perinatal period is regarded as the most important “window of opportunity” for imprinting metabolism and immunity, preterm birth may have long-term consequences for the development of immune-mediated diseases. Intriguingly, preterm neonates appear to develop bronchial asthma more frequently, but atopic dermatitis less frequently in comparison to term neonates. The longitudinal study of preterm neonates could offer important insights into the process of imprinting for immune-mediated diseases. On the one hand, preterm birth may interrupt influences of the intrauterine environment on the fetus that increase or decrease the risk of later immune disease (e.g., maternal antibodies and placenta-derived factors), whereas on the other hand, it may lead to the premature exposure to protective or harmful extrauterine factors such as microbiota and nutritional antigen. Solving this puzzle may help unravel new preventive and therapeutic approaches for immune diseases.

Balancing Tolerance or Allergy to Food Proteins

Dietary proteins usually induce immune tolerance, but may trigger life-threatening immune responses in the case of food allergy. The associated type 2 immunity, linked with specific IgE production and the activation of mast cells and basophils, is well understood but the mechanisms related to preventing food allergy are still being deciphered. Recent insights into the mechanisms that regulate oral tolerance and dietary antigen sampling have revealed unique regulatory events that occur during early life and into adulthood. Drawing from both recent clinical and experimental discoveries, this article focuses on current evidence for how several key stages of life present mechanistic points that might participate in tipping the balance between food protein tolerance and allergy.