Food allergy: could the gut microbiota hold the key?

Human milk oligosaccharides in preventing food allergy: A review through gut microbiota and immune regulation

Food allergy (FA) has increasingly attracted global attention in past decades. However, the mechanism and effect of FA are complex and varied, rendering it hard to prevention and management. Most of the allergens identified so far are macromolecular proteins in food and may have potential cross-reactions. Human milk oligosaccharides (HMOs) have been regarded as an ideal nutrient component for infants, as they can enhance the immunomodulatory capacity to inhibit the progress of FA. HMOs may intervene in the development of allergies by modifying gut microbiota and increasing specific short-chain fatty acids levels. Additionally, HMOs could improve the intestinal permeability and directly or indirectly regulate the balance of T helper cells and regulatory T cells by enhancing the inflammatory signaling pathways to combat FA. This review will discuss the influence factors of FA, key species of gut microbiota involved in FA, types of FA, and profiles of HMOs and provide evidence for future research trends to advance HMOs as potential therapeutic aids in preventing the progress of FA.

Improved viability of probiotics by encapsulation in chickpea protein matrix during simulated gastrointestinal digestion by succinylated modification

The potential application of succinylated chickpea protein (SCP) as a wall material for spray-dried microencapsulated probiotics was investigated. The results showed that succinylation increased the surface charge of chickpea proteins (CP) and reduced the particle size of the proteins. Meanwhile, succinylated modification decreased the solubility of protein under acidic conditions and increased the solubility in alkaline conditions. The effects of spray drying and in vitro gastrointestinal digestion on probiotics were investigated by microencapsulating chickpea protein with different degrees of N-succinylation. The results showed that all microcapsules had similar morphology, particle size and low water content. The microcapsules prepared by succinylated chickpea protein showed better stability and viability during spray drying and gastrointestinal digestion. The protective effect of probiotics was better as the degree of N-succinylation increased. In particular, the SCP-3-P sample (10 % succinic anhydride modified CP and maltodextrin) lost only 0.29 Log CFU/g throughout gastrointestinal digestion. The superior protective effect provided by succinylated CP in simulated gastric fluid (SGF) was mainly attributed to the reaction of succinic anhydride with protein to cause protein aggregation under gastric acidic conditions, reducing the infiltration of gastric acid and pepsin and maintaining the structural integrity of the microcapsules. Therefore, these findings provide a new strategy for probiotic intestinal delivery and application of chickpea protein.

Integrating Widely Targeted Lipidomics and Transcriptomics Unravels Aberrant Lipid Metabolism and Identifies Potential Biomarkers of Food Allergies in Rats

SCOPE

Oral food challenges (OFCs) are currently the gold standard for determining the clinical reactivity of food allergy (FA) but are time-consuming, expensive, and risky. To screen novel peripheral biomarkers of FA and characterize the aberrant lipid metabolism in serum, 24 rats are divided into four groups: peanut, milk, and shrimp allergy (PA, MA, and SA, respectively) and control groups, with six rats in each group, and used for widely targeted lipidomics and transcriptomics analysis.

METHODS AND RESULTS

Widely targeted lipidomics reveal 144, 162, and 206 differentially accumulated lipids in PA, MA, and SA groups, respectively. The study integrates widely targeted lipidomics and transcriptomics and identifies abnormal lipid metabolism correlated with widespread differential accumulation of diverse lipids (including triacylglycerol, diacylglycerol, sphingolipid, and glycerophospholipid) in PA, MA, and SA. Simplified random forest classifier is constructed through five repetitions of 10-fold cross-validation to distinguish allergy from control. A subset of 15 lipids as potential biomarkers allows for more reliable and more accurate prediction of FA. Independent replication validates the reproducibility of potential biomarkers.

CONCLUSION

The results reveal the major abnormalities in lipid metabolism and suggest the potential role of lipids as novel molecular signatures for FA.

Berberine-containing natural-medicine with boiled peanut-OIT induces sustained peanut-tolerance associated with distinct microbiota signature

Background

Gut microbiota influence food allergy. We showed that the natural compound berberine reduces IgE and others reported that BBR alters gut microbiota implying a potential role for microbiota changes in BBR function.

Objective

We sought to evaluate an oral Berberine-containing natural medicine with a boiled peanut oral immunotherapy (BNP) regimen as a treatment for food allergy using a murine model and to explore the correlation of treatment-induced changes in gut microbiota with therapeutic outcomes.

Methods

Peanut-allergic (PA) mice, orally sensitized with roasted peanut and cholera toxin, received oral BNP or control treatments. PA mice received periodic post-therapy roasted peanut exposures. Anaphylaxis was assessed by visualization of symptoms and measurement of body temperature. Histamine and serum peanut-specific IgE levels were measured by ELISA. Splenic IgE+B cells were assessed by flow cytometry. Fecal pellets were used for sequencing of bacterial 16S rDNA by Illumina MiSeq. Sequencing data were analyzed using built-in analysis platforms.

Results

BNP treatment regimen induced long-term tolerance to peanut accompanied by profound and sustained reduction of IgE, symptom scores, plasma histamine, body temperature, and number of IgE+ B cells (p <0.001 vs Sham for all). Significant differences were observed for Firmicutes/Bacteroidetes ratio across treatment groups. Bacterial genera positively correlated with post-challenge histamine and PN-IgE included Lachnospiraceae, Ruminococcaceae, and Hydrogenanaerobacterium (all Firmicutes) while Verrucromicrobiacea. Caproiciproducens, Enterobacteriaceae, and Bacteroidales were negatively correlated.

Conclusions

BNP is a promising regimen for food allergy treatment and its benefits in a murine model are associated with a distinct microbiota signature.

Effect of Peanut Protein Treated with Alkaline Protease and Flavorzyme on BALB/c Mice

This article aims to analyze the effects of enzyme treatment concentration, temperature, and time on peanut protein so as to obtain an optimal enzymatic hydrolysis condition for flavorzyme (Fla) and alkaline protease (Alk). The results were as follows: enzymatic hydrolysis temperature 60 °C and 55 °C, enzyme concentration 10% and 4%, enzymatic hydrolysis time 80 min and 60 min, and double enzyme hydrolysis ratio 2% Fla + 5% Alk, respectively. The BALB/c mice were sensitized with gavage of peanut protein before and after enzyme treatment to evaluate the effects of different enzyme treatments on peanut allergenicity. Compared with the mice sensitized with raw peanuts, the weight growth rate of the mice sensitized with enzyme treatment peanut increased but not as much as the control, the degranulation degree of mast cell and basophils decreased, the inflammatory infiltration and congestion in jejunum and lung tissue decreased, the expression of proinflammatory factors and thymic stromal lymphopoietin (TSLP) gene decreased, and the secretion of specific antibodies (IgE, and IgG) decreased, and the binding ability of peanut protein with peanut-specific IgE antibodies decreased as well. The results above indicate that the allergenicity of peanut protein decreases after enzyme treatment and the dual enzyme (Fla + Alk) treatment can be much more efficient.

Molecular structure, IgE binding capacity and gut microbiota of ovalbumin conjugated to fructose and galactose:A comparative study

Ovalbumin (OVA) was modified by fructose (Fru) and galactose (Gal) to study the structure, IgG/IgE binding capacity and effects on human intestinal microbiota of the conjugated products. Compared with OVA-Fru, OVA-Gal has a lower IgG/IgE binding capacity. The reduction of OVA is not only associated with the glycation of R84, K92, K206, K263, K322 and R381 in the linear epitopes, but also with conformational epitope changes, manifested as secondary and tertiary structural changes caused by Gal glycation. In addition, OVA-Gal could alter the structure and abundance of gut microbiota at phylum, family, and genus levels and restore the abundance of bacteria associated with allergenicity, such as Barnesiella, Christensenellaceae_R-7_group, and Collinsela, thereby reducing allergic reactions. These results indicate that OVA-Gal glycation can reduce the IgE binding capacity of OVA and change the structure of human intestinal microbiota. Therefore, Gal glycation may be a potential method to reduce protein allergenicity.

Protective Role of Vaccination against Tuberculosis and Hepatitis B in Prevention of Atopic Dermatitis: Report on Intermediate Results of Prospective Cohort Study

Background. Studies have shown that vaccination in the first hours/days after birth shifts the immune response from intrauterine Th2 towards Th1-type activation and reduces the risk of atopic conditions. However, we did not find published data from prospective studies on this topic.

Objective. The aim of the study is to define the presence of negative correlation between vaccination against tuberculosis and hepatitis B in the first hours/days of life and atopic dermatitis development in infants.

Methods. Continuous prospective study of children cohort born from April to June 2021 and observed in one outpatient’s clinic was carried out. Data from 307 infant’s records (F. 112/y), vaccination record cards (F. 063/y), prenatal and delivery records (F. 113/y-20, section № 3), and neonatal discharge summaries were analyzed for the decreed period. The child vaccination status (by the time of vaccination against tuberculosis and hepatitis B), presence of risk factors for allergic disease development, and presence of atopic dermatitis were evaluated.

Results. Atopic dermatitis (AD) was significantly less likely to be diagnosed by the age of 1 year in infants from the group of BCG-M vaccinated at maternity hospital than in those vaccinated later or not vaccinated at all (15.2% versus 66% and 35.7%, respectively; p < 0,01). AD was less likely to develop in children with risk factors for allergic disease who were vaccinated against tuberculosis in the maternity hospital than in those vaccinated later or unvaccinated at all (18, 75 and 62.5%, respectively; p < 0.01). The ratio of children with diagnosed AD by the age of 12 months was significantly less in the group of children vaccinated against hepatitis B in the maternity hospital than in those vaccinated later or unvaccinated at all (17.6, 44.9 and 31.8%, respectively; p < 0.01). These ratios for children with risk of allergic disease development were 24%, 50% and 44.4%, respectively (p = 0.043). It has also been shown that timely vaccination with both vaccines in the early neonatal period significantly reduces the risk of AD in general infant population compared to non-vaccinated individuals or those who had only one vaccine (odds ratio [OR] 0.374; 95% confidence interval [CI] 0.253-0.552; p < 0.01). Whereas the disease development in children with allergic risk is less likely with timely vaccination (20.8% versus 53.3%; OR = 0.252; 95% CI 0.145–0.440; OR = 0.374; 95% CI 0,253–0,552; p < 0,01).

Conclusion. The obtained results may indicate possible risk reduction for AD development due to timely preventive vaccination against tuberculosis and hepatitis B, especially in children with allergic risk. The study is currently ongoing. 

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

Gut microbiome modulation by probiotics, prebiotics, synbiotics and postbiotics: a novel strategy in food allergy prevention and treatment

Food allergy has caused lots of global public health issues, particularly in developed countries. Presently, gut microbiota has been widely studied on allergy, while the role of dysbiosis in food allergy remains unknown. Scientists found that changes in gut microbial compositions and functions are strongly associated with a dramatic increase in the prevalence of food allergy. Altering microbial composition is crucial in modulating food antigens' immunogenicity. Thus, the potential roles of probiotics, prebiotics, synbiotics, and postbiotics in affecting gut bacteria communities and the immune system, as innovative strategies against food allergy, begins to attract high attention of scientists. This review briefly summarized the mechanisms of food allergy and discussed the role of the gut microbiota and the use of probiotics, prebiotics, synbiotics, and postbiotics as novel therapies for the prevention and treatment of food allergy. The perspective studies on the development of novel immunotherapy in food allergy were also described. A better understanding of these mechanisms will facilitate the development of preventive and therapeutic strategies for food allergy.

Fucoxanthin Prevents the Ovalbumin-Induced Food Allergic Response by Enhancing the Intestinal Epithelial Barrier and Regulating the Intestinal Flora

This study aimed to determine whether fucoxanthin alleviated ovalbumin (OVA)-induced food allergy (FA) and explored the possible mechanisms. The results indicated that supplementation with fucoxanthin at 10.0-20.0 mg/kg per day for 7 weeks inhibited food anaphylaxis and the production of immunoglobulin (Ig) E, IgG, histamine, and related cytokines while alleviating allergic symptoms in sensitized mice. Fucoxanthin enhanced the intestinal epithelial barrier by up-regulating tight junction (TJ) protein expression and promoting regenerating islet-derived protein III-gamma (RegIIIγ) and secretory IgA (sIgA) secretion. In addition, fucoxanthin induced the secretion of anti-inflammatory factors (interleukin (IL)-10 and transforming growth factor β (TGF-β)) by regulatory T (Treg) cells and decreased the pro-inflammatory factor levels (IL-4, tumor necrosis factor-α (TNF-α), IL-17, and IL-1β), ameliorating intestinal inflammation. Compared with the model group, beneficial bacteria, such as Lactobacillaceae, increased in the intestinal flora, while pathogenic bacteria like Helicobacteraceae, Desulfovibrionaceae, and Streptococcaceae decreased. Therefore, fucoxanthin may effectively prevent FA by enhancing the intestinal epithelial barrier and reshaping the intestinal flora.

IgE-Mediated food allergy: Current diagnostic modalities and novel biomarkers with robust potential

Food allergy (FA) is a serious public health issue afflicting millions of people globally, with an estimated prevalence ranging from 1-10%. Management of FA is challenging due to overly restrictive diets and the lack of diagnostic approaches with high accuracy and prediction. Although measurement of serum-specific antibodies combined with patient medical history and skin prick test is a useful diagnostic tool, it is still an imprecise predictor of clinical reactivity with a high false-positive rate. The double-blind placebo-controlled food challenge represents the gold standard for FA diagnosis; however, it requires large healthcare and involves the risk of acute onset of allergic reactions. Improvement in our understanding of the molecular mechanism underlying allergic disease pathology, development of omics-based methods, and advances in bioinformatics have boosted the generation of a number of robust diagnostic biomarkers of FA. In this review, we discuss how traditional diagnostic modalities guide appropriate diagnosis and management of FA in clinical practice, as well as uncover the potential of the latest biomarkers for the diagnosis, monitoring, and prediction of FA. We also raise perspectives for precise and targeted medical intervention to fill the gap in the diagnosis of FA.

Epithelial barrier hypothesis: Effect of the external exposome on the microbiome and epithelial barriers in allergic disease

Environmental exposure plays a major role in the development of allergic diseases. The exposome can be classified into internal (e.g., aging, hormones, and metabolic processes), specific external (e.g., chemical pollutants or lifestyle factors), and general external (e.g., broader socioeconomic and psychological contexts) domains, all of which are interrelated. All the factors we are exposed to, from the moment of conception to death, are part of the external exposome. Several hundreds of thousands of new chemicals have been introduced in modern life without our having a full understanding of their toxic health effects and ways to mitigate these effects. Climate change, air pollution, microplastics, tobacco smoke, changes and loss of biodiversity, alterations in dietary habits, and the microbiome due to modernization, urbanization, and globalization constitute our surrounding environment and external exposome. Some of these factors disrupt the epithelial barriers of the skin and mucosal surfaces, and these disruptions have been linked in the last few decades to the increasing prevalence and severity of allergic and inflammatory diseases such as atopic dermatitis, food allergy, allergic rhinitis, chronic rhinosinusitis, eosinophilic esophagitis, and asthma. The epithelial barrier hypothesis provides a mechanistic explanation of how these factors can explain the rapid increase in allergic and autoimmune diseases. In this review, we discuss factors affecting the planet's health in the context of the 'epithelial barrier hypothesis,' including climate change, pollution, changes and loss of biodiversity, and emphasize the changes in the external exposome in the last few decades and their effects on allergic diseases. In addition, the roles of increased dietary fatty acid consumption and environmental substances (detergents, airborne pollen, ozone, microplastics, nanoparticles, and tobacco) affecting epithelial barriers are discussed. Considering the emerging data from recent studies, we suggest stringent governmental regulations, global policy adjustments, patient education, and the establishment of individualized control measures to mitigate environmental threats and decrease allergic disease.

Food Allergy-Induced Autism-Like Behavior is Associated with Gut Microbiota and Brain mTOR Signaling

Purpose

Food allergy-induced autism-like behavior has been increasing for decades, but the causal drivers of this association are unclear. We sought to test the association of gut microbiota and mammalian/mechanistic target of rapamycin (mTOR) signaling with cow’s milk allergy (CMA)-induced autism pathogenesis.

Methods

Mice were sensitized intragastrically with whey protein containing cholera toxin before sensitization on intraperitoneal injection with whey-containing alum, followed by intragastric allergen challenge to induce experimental CMA. The food allergic immune responses, ASD-like behavioral tests and changes in the mTOR signaling pathway and gut microbial community structure were performed.

Results

CMA mice showed autism-like behavioral abnormalities and several distinct biomarkers. These include increased levels of 5-hydroxymethylcytosine (5-hmC) in the hypothalamus; c-Fos were predominantly located in the region of the lateral orbital prefrontal cortex (PFC), but not ventral; decreased serotonin 1A in amygdala and PFC. CMA mice exhibited a specific microbiota signature characterized by coordinate changes in the abundance of taxa of several bacterial genera, including the Lactobacillus. Interestingly, the changes were accompanied by promoted mTOR signaling in the brain of CMA mice.

Conclusion

We found that disease-associated microbiota and mTOR activation may thus play a pathogenic role in the intestinal, immunological, and psychiatric Autism Spectrum Disorder (ASD)-like symptoms seen in CAM associated autism. However, this is only a preliminary study, and their mechanisms require further investigation.

Probiotics Regulate Gut Microbiota: An Effective Method to Improve Immunity

Probiotics are beneficial active microorganisms that colonize the human intestines and change the composition of the flora in particular parts of the host. Recently, the use of probiotics to regulate intestinal flora to improve host immunity has received widespread attention. Recent evidence has shown that probiotics play significant roles in gut microbiota composition, which can inhibit the colonization of pathogenic bacteria in the intestine, help the host build a healthy intestinal mucosa protective layer, and enhance the host immune system. Based on the close relationship between the gut microbiota and human immunity, it has become an extremely effective way to improve human immunity by regulating the gut microbiome with probiotics. In this review, we discussed the influence of probiotics on the gut microbiota and human immunity, and the relationship between immunity, probiotics, gut microbiota, and life quality. We further emphasized the regulation of gut microflora through probiotics, thereby enhancing human immunity and improving people’s lives.

Probiotics ameliorate alveolar bone loss by regulating gut microbiota

OBJECTIVES

Oestrogen deficiency is an aetiological factor of postmenopausal osteoporosis (PMO), which not only decreases bone density in vertebrae and long bone but also aggravates inflammatory alveolar bone loss. Recent evidence has suggested the critical role of gut microbiota in osteoimmunology and its influence on bone metabolisms. The present study aimed to evaluate the therapeutic effects of probiotics on alveolar bone loss under oestrogen-deficient condition.

MATERIALS AND METHODS

Inflammatory alveolar bone loss was established in ovariectomized (OVX) rats, and rats were daily intragastrically administered with probiotics until sacrifice. Gut microbiota composition, intestinal permeability, systemic immune status and alveolar bone loss were assessed to reveal the underlying correlation between gut microbiota and bone metabolisms.

RESULTS

We found administration of probiotics significantly prevented inflammatory alveolar bone resorption in OVX rats. By enriching butyrate-producing genera and enhancing gut butyrate production, probiotics improved intestinal barrier and decreased gut permeability in the OVX rats. Furthermore, the oestrogen deprivation-induced inflammatory responses were suppressed in probiotics-treated OVX rats, as reflected by reduced serum levels of inflammatory cytokines and a balanced distribution of CD4+ IL-17A+ Th17 cells and CD4+ CD25+ Foxp3+ Treg cells in the bone marrow.

CONCLUSIONS

This study demonstrated that probiotics can effectively attenuate alveolar bone loss by modulating gut microbiota and further regulating osteoimmune response and thus represent a promising adjuvant in the treatment of alveolar bone loss under oestrogen deficiency.

Food irradiation: a promising technology to produce hypoallergenic food with high quality

The increasing incidence of food allergy cases is a public health problem of global concern. Producing hypoallergenic foods with high quality, low cost, and eco-friendly is a new trend for the food industry in the coming decades. Food irradiation, a non-thermal food processing technology, is a powerful tool to reduce the allergenicity with the above advantages. This review presents a summary of recent studies about food irradiation to reduce the allergenicity of food, including shellfish, soy, peanut, milk, tree nut, egg, wheat and fish. Principles of food irradiation, including mechanisms of allergenicity-reduction, irradiation types and characteristics, are discussed. Specific effects of food irradiation are also evaluated, involving microbial decontamination, improvement or preservation of nutritional value, harmful substances reduction of food products. Furthermore, the advantages, disadvantages and limitations of food irradiation are analyzed. It is concluded that food irradiation is a safety tool to reduce the allergenicity of food effectively, with high nutritional value and long shelf-life, making it a competitive alternative technology to traditional techniques such as heating treatments. Of note, a combination of irradiation with additional processing may be a trend for food irradiation.

Depolymerized sulfated galactans from Eucheuma serra ameliorate allergic response and intestinal flora in food allergic mouse model

The ameliorative effect of depolymerized sulfated polysaccharides from Eucheuma serra (DESP) on ovalbumin (OVA)-caused induced food allergy was investigated in this work. Results showed that OVA stimulated the secretion of allergy-related cytokines (OVA-specific IgE, mMCP-1, IgA, TNF-α) and led to diarrhea, intestinal epithelial damage, and intestinal microflora dysbiosis in sensitized mice. After the administration of DESP, however, the anaphylactic symptoms (shortness of breath, hypothermia, diarrhea), along with the allergy-related cytokines, were effectively suppressed. Moreover, the reduced intestinal inflammation was discovered in the DESP-treated group. Additionally, 16S rRNA sequencing of fecal samples was performed, and gene count and α-diversity analysis revealed that DESP improved microbial community richness. Taxonomic composition analysis showed that DESP modulated the proportion of Firmicutes and Bacteroidetes/Proteobacteria. Particularly, DESP increased probiotics (Lactobacillaceae, Bifidobacteriaceae and Prevotellaceae) and decreased pathogenic bacteria (Helicobacteraceae and Desulfovibrionaceae). These findings, therefore, suggest that DESP may ameliorate food allergy through the regulation of intestinal microbiota.

Emerging Food Allergy Biomarkers

The management of food allergy is complicated by the lack of highly predictive biomarkers for diagnosis and prediction of disease course. The measurement of food-specific IgE is a useful tool together with clinical history but is an imprecise predictor of clinical reactivity. The gold standard for diagnosis and clinical research is a double-blind placebo-controlled food challenge. Improvement in our understanding of immune mechanisms of disease, development of high-throughput technologies, and advances in bioinformatics have yielded a number of promising new biomarkers of food allergy. In this review, we will discuss advances in immunoglobulin measurements, the utility of the basophil activation test, T-cell profiling, and the use of -omic technologies (transcriptome, epigenome, microbiome, and metabolome) as biomarker tools in food allergy.

Role of the Microbiome in Allergic Disease Development

PURPOSE OF REVIEW

Evidence suggests that the microbiome of the skin, gastrointestinal tract, and airway contribute to health and disease. As we learn more about the role that the microbiota plays in allergic disease development, we can develop therapeutics to alter this pathway.

RECENT FINDINGS

Epidemiologic studies reveal that an association exists between environmental exposures, which alter the microbiota, and developing atopic dermatitis, food allergy, and/or asthma. In fact, samples from the skin, gastrointestinal tract, and respiratory tract reveal distinct microbiotas compared with healthy controls, with microbial changes (dysbiosis) often preceding the development of allergic disease. Mechanistic studies have confirmed that microbes can either promote skin, gut, and airway health by strengthening barrier integrity, or they can alter skin integrity and damage gut and airway epithelium. In this review, we will discuss recent studies that reveal the link between the microbiota and immune development, and we will discuss ways to influence these changes.

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.

Food allergy and the microbiome: Current understandings and future directions

Growing evidence points to an important role for the commensal microbiota in susceptibility to food allergy. Epidemiologic studies demonstrate associations between exposures known to modify the microbiome and risk of food allergy. Direct profiling of the gut microbiome in human cohort studies has demonstrated that individuals with food allergy have distinct gut microbiomes compared to healthy control subjects, and dysbiosis precedes the development of food allergy. Mechanistic studies in mouse models of food allergy have confirmed that the composition of the intestinal microbiota can imprint susceptibility or resistance to food allergy on the host and have identified a unique population of microbially responsive RORγt-positive FOXp3-positive regulatory T cells as critical for the maintenance of tolerance to foods. Armed with this new understanding of the role of the microbiota in food allergy and tolerance, therapeutics aimed at modifying the gastrointestinal microbiota are in development. In this article we review key milestones in the development of our current understanding of how the gastrointestinal microbiota contributes to food allergy and discuss our vision for the future of the field.

Immunomodulatory effects of breast milk on food allergy

OBJECTIVE

To summarize the literature on immunomodulatory effects of breast milk on sensitization and possible mechanisms of action.

DATA SOURCES

Animal and human studies in PubMed that assessed breastfeeding or breast milk composition in food allergy.

STUDY SELECTIONS

All recent studies and some older key publications focusing on this topic.

RESULTS

Human milk composition is highly variable among mothers, which can affect the developing infant immune system. Human milk also affects the infant gut microbiome, which is associated with food allergy. High levels of human milk immune factors (IgA, cytokines, oligosaccharides) are associated with reduced risk of food allergy in the infant; it remains uncertain whether these are directly protective or biomarkers of transferred protection. Animal studies highlight potential mechanisms of protection provided by antigens, transforming growth factor β, and immunocomplexes, yet their relevance is poorly understood in humans. The role of food antigens in human milk in initial sensitization or tolerance induction is unclear.

CONCLUSION

The protection against allergy development provided by human milk may be attributable to the effect on the infant gut microbiome or direct effects on immune system. Studies evaluating the effect of breastfeeding and human milk composition on food allergy are needed.