Early-life risk factors for food allergy: Dietary and environmental factors revisited

Extracellular adenosine triphosphate: A new gateway for food allergy mechanism research?

Although various studies have been conducted, the detailed mechanisms of food allergy remain a topic of ongoing debate. Recently, researchers have reported that extracellular adenosine triphosphate (eATP), a member of damage-associated molecular patterns secreted by stressed cells, plays a critical role in the progression of asthma and atopic dermatitis. These studies suggest that dysregulated eATP significantly influences various aspects of disease progression, from bodily sensitization to the emergence of clinical manifestations. Given the shared pathogenic mechanisms among asthma, atopic dermatitis, and food allergies, we hypothesize that eATP may also serve as a crucial regulator in the development of food allergies. To elucidate this hypothesis, we first summarize the evidence and limitations of food allergy theories, then discuss the roles of eATP in allergic diseases. We conclude with speculative insights into the potential influence of eATP on food allergy development, aiming to inspire further investigation into the molecular mechanisms of food allergies.

Uncovering the mechanisms underlying the efficacy of probiotic strains in mitigating food allergies: an emphasis on gut microbiota and indoleacrylic acid

Food allergies manifest as systemic or digestive allergic responses induced by food allergens, and their progression has been demonstrated to be intimately associated with the host's gut microbiota. Our preceding investigation has revealed that the probiotic strains Lactiplantibacillus plantarum CCFM1189 and Limosilactobacillus reuteri CCFM1190 possess the capability to mitigate the symptoms of food allergy in mice. However, the underlying mechanisms and material foundations through which these probiotic strains exert their effects remain enigmatic. Here, we initially compared the ameliorative effects of these two probiotic strains on food allergy mice subjected to antibiotic cocktail (ABX) treatment. It is indicated that ABX treatment was ineffective in alleviating weight loss, diarrhea, and allergic symptoms in mice, and it also inhibited the reduction of histamine and T helper cell 2 (Th2) cytokines mediated by effective strains, suggesting that effective strains must operate through the gut microbiota. Then, building upon the outcomes of prior non-targeted metabolomics studies, by quantifying the content of indoleacrylic acid (IA) in single-strain fermentation of probiotic strains and mouse feces, it was ascertained that effective strains do not synthesize IA themselves but can augment the concentration of IA in the gut by modulating the gut microbiota. Ultimately, we discovered that direct intervention with IA could mitigate diarrhea, allergic symptoms, and intestinal damage by modulating immunoglobulin E (IgE) levels, histamine, Th2 cytokines, and tight junction proteins, thereby corroborating that IA is a pivotal metabolite for the alleviation of food allergies. These observations underscore the significance of gut microbiota and metabolites like IA in the management of food allergies and hold potential implications for the development of novel therapeutic strategies.

Protein-bound AGEs derived from methylglyoxal induce pro-inflammatory response and barrier integrity damage in epithelial cells by disrupting the retinol metabolism

Advanced glycation end-products (AGEs) are complex and heterogeneous compounds widely present in processed foods. Previous studies evidenced the adverse effects of AGEs on gut homeostasis, but the precise pathological mechanisms and molecular pathways responsible for the disruption of intestinal barrier integrity by AGEs remain incompletely elucidated. In this study, protein-bound AGEs (BSA-MGO), the most common type of dietary AGE, were prepared by methylglyoxal-mediated glycation, and an in vitro human epithelial colorectal adenocarcinoma (Caco-2) cell model was employed to evaluate the impact of protein-bound AGEs on gut epithelial function. Results showed that exposure to BSA-MGO significantly increased the permeability of Caco-2 cell monolayers as evidenced by the decreased transepithelial electrical resistance value, increased paracellular transport of FITC-dextran, and down-regulated tight-junction proteins. In parallel, BSA-MGO induced pro-inflammatory responses and oxidative stress in the monolayers. Transcriptomic profiling further revealed that BSA-MGO disrupted the retinol metabolism, thereby contributing to the barrier integrity damage in epithelial cells. Overall, these results provide valuable insights into the disrupting effects of dietary AGEs on intestinal barrier function, and the perturbed pathways present potential targets for further exploration of the molecular mechanisms underlying the detrimental effect of processed foods on gut health.

Metabolomics identifies phenotypic biomarkers of amino acid metabolism in milk allergy and sensitized tolerance

BACKGROUND

A substantial proportion of sensitized individuals tolerate suspected foods without developing allergic symptoms; this phenomenon is known as sensitized tolerance. The immunogenic and metabolic features underlying the sensitized-tolerant phenotype remain largely unknown.

OBJECTIVE

We aimed to uncover the metabolic signatures associated with clinical milk allergy (MA) and sensitized tolerance using metabolomics.

METHODS

We characterized the serum metabolic and immunologic profiles of children with clinical IgE-mediated MA (n = 30) or milk-sensitized tolerance (n = 20) and healthy controls (n = 21). A comparative analysis was performed to identify dysregulated pathways associated with the clinical manifestations of food allergy. We also analyzed specific biomarkers indicative of different sensitization phenotypes in children with MA. The candidate metabolites were validated in an independent quantification cohort (n = 41).

RESULTS

Metabolomic profiling confirmed the presence of a distinct metabolic signature that discriminated children with MA from those with milk-sensitized tolerance. Amino acid metabolites generated via arginine, proline, and glutathione metabolism were uniquely altered in children with sensitized tolerance. Arginine depletion and metabolism through the polyamine pathway to fuel glutamate synthesis were closely associated with suppression of clinical symptoms in the presence of allergen-specific IgE. In children with MA, the polysensitized state was characterized by disturbances in tryptophan metabolism.

CONCLUSIONS

By combining untargeted metabolomics with targeted validation in an independent quantification cohort, we identified candidate metabolites as phenotypic and diagnostic biomarkers of food allergy. Our results provide insights into the pathologic mechanisms underlying childhood allergy and suggest potential therapeutic targets.

Dietary Polyphenols, Plant Metabolites, and Allergic Disorders: A Comprehensive Review

Given the ongoing rise in the occurrence of allergic disorders, alterations in dietary patterns have been proposed as a possible factor contributing to the emergence and progression of these conditions. Currently, there is a significant focus on the development of dietary therapies that utilize natural compounds possessing anti-allergy properties. Dietary polyphenols and plant metabolites have been intensively researched due to their well-documented anti-inflammatory, antioxidant, and immunomodulatory characteristics, making them one of the most prominent natural bioactive chemicals. This study seeks to discuss the in-depth mechanisms by which these molecules may exert anti-allergic effects, namely through their capacity to diminish the allergenicity of proteins, modulate immune responses, and modify the composition of the gut microbiota. However, further investigation is required to fully understand these effects. This paper examines the existing evidence from experimental and clinical studies that supports the idea that different polyphenols, such as catechins, resveratrol, curcumin, quercetin, and others, can reduce allergic inflammation, relieve symptoms of food allergy, asthma, atopic dermatitis, and allergic rhinitis, and prevent the progression of the allergic immune response. In summary, dietary polyphenols and plant metabolites possess significant anti-allergic properties and can be utilized for developing both preventative and therapeutic strategies for targeting allergic conditions. The paper also discusses the constraints in investigating and broad usage of polyphenols, as well as potential avenues for future research.

Dietary Polyphenols-Natural Bioactive Compounds with Potential for Preventing and Treating Some Allergic Conditions

In light of the constantly increasing prevalence of allergic diseases, changes in dietary patterns have been suggested as a plausible environmental explanation for the development and progression of these diseases. Nowadays, much attention has been paid to the development of dietary interventions using natural substances with anti-allergy activities. In this respect, dietary polyphenols have been studied extensively as one of the most prominent natural bioactive compounds with well-documented anti-inflammatory, antioxidant, and immunomodulatory properties. This review aims to discuss the mechanisms underlying the potential anti-allergic actions of polyphenols related to their ability to reduce protein allergenicity, regulate immune response, and gut microbiome modification; however, these issues need to be elucidated in detail. This paper reviews the current evidence from experimental and clinical studies confirming that various polyphenols such as quercetin, curcumin, resveratrol, catechins, and many others could attenuate allergic inflammation, alleviate the symptoms of food allergy, asthma, and allergic rhinitis, and prevent the development of allergic immune response. Conclusively, dietary polyphenols are endowed with great anti-allergic potential and therefore could be used either for preventive approaches or therapeutic interventions in relation to allergic diseases. Limitations in studying and widespread use of polyphenols as well as future research directions are also discussed.