The role of casein-specific IgA and TGF-β in children with food protein-induced enterocolitis syndrome to milk

Identification of Gut Biomarkers of FPIES in a Longitudinal Comparative Pediatric Study

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated allergy without known biomarkers. We aimed to compare fecal biomarkers related to gut inflammation and immunity in children with FPIES, with resolved FPIES (tolerant), and in matched controls.

METHODS

Stools were collected from FPIES children on elimination diet, before and after an oral food challenge (OFC) performed to assess their natural tolerance, at the end of a follow-up in tolerant FPIES children, and in matched controls (1:1 ratio). Concentrations of calprotectin, EDN (eosinophilic derived neurotoxin), and secretory IgA (sIgA) underwent comparative paired analysis.

RESULTS

Thirty-eight patients were included (age: 1.3 years old, interquartile range: IQR [0.9-2.0]), of which 22 became tolerant during follow-up. Upon inclusion, allergic patients and controls had similar concentrations of calprotectin (38 μg/g [8-85] vs. 27 μg/g [11-46], p = 0.15) and EDN (504 ng/g [275-1252] vs. 516 ng/g [215-844], p = 0.86). However, concentrations of these inflammatory biomarkers increased transiently after a failed OFC (p < 0.001 and p = 0.01 respectively), without correlating with the severity of an allergic reaction. sIgA were higher in allergic than in tolerant patients: 2224 μg/g [878-3529] vs. 794 μg/g [699-1767] (p < 0.01). Calprotectin, EDN, and sIgA were comparable in tolerant patients and controls. sIgA less than 2637 μg/g had a negative predictive value of 75.3% for the differentiation allergic patients from tolerant patients and controls (area under curve: 0.63, 95% CI: 0.52-0.74).

CONCLUSION

A few days after an acute allergic reaction, there was no detectable chronic gut inflammation in FPIES. sIgA may be a useful tool for clinicians in timing OFC.

The Role of IgE Sensitization in Acute FPIES: A Systematic Review and Meta-Analysis

BACKGROUND

Evidence on the role of immunoglobulin E (IgE) sensitization in acute food protein-induced enterocolitis syndrome (atypical FPIES) is limited. Initial reports claimed association with persistent disease; however, recent studies have not replicated this.

OBJECTIVE

To systematically review the relationship between sensitization to the culprit food(s) in acute FPIES and the outcome of follow-up oral food challenges. To assess the rates of sensitization, seroconversion (ie, switch from negative tests to sensitization), and phenotype switch to IgE-mediated food allergy over time in individuals with acute FPIES.

METHODS

Systematic review searching 10 databases. Studies of children and adults with an acute FPIES diagnosis assessing IgE sensitization to a culprit food at onset or follow-up measured by skin prick or serological test were included.

RESULTS

Of 1,830 studies identified, 53 were eligible including 3,514 participants. Ten studies had an analytical design assessing whether sensitization was associated with disease persistence, with 4 showing an association and 6 showing no association. In individuals with acute FPIES, the sensitization rate was 9.8% (95% confidence interval [95% CI 7.4%-12.1%; 34 studies, 2,587 participants, I2 = 82%); the frequency of seroconversion was 1.1% (95% CI 0.1%-2.1%; 9 studies, 673 participants, I2 = 32%); and phenotype switch occurred in 1.1% (95% CI 0.4%-1.7%; 14 studies, 935 participants, I2 = 0%) and 13% (95% CI 5.5%-20.5%, 12 studies, 93 participants; I2 = 18%) of sensitized participants.

CONCLUSIONS

We did not find consistent evidence for the relationship between IgE sensitization and FPIES persistence. We found phenotype switch to IgE-mediated food allergy is uncommon in acute FPIES. An IgE sensitization in FPIES does not have a clear relationship with clinical outcomes.

Oral Food Challenge Protocols in Food Protein-Induced Enterocolitis Syndrome: A Systematic Review

BACKGROUND

Oral food challenges (OFCs) are essential for the diagnosis and follow-up of acute food protein-induced enterocolitis syndrome (FPIES) because no diagnostic or prognostic biomarkers are available. However, the optimal OFC procedure remains unclear.

OBJECTIVE

This systematic review aimed to assess OFC procedures' design and clinical outcomes in patients with FPIES.

METHODS

We searched 10 databases for studies published in English between 1978 and February 2024 involving children or adults undergoing OFC for FPIES. Critical appraisal followed Effective Public Health Practice Project parameters.

RESULTS

In total, 52 studies met inclusion criteria, all observational studies. Of these, 35 were judged to have strong methodological quality. There was great heterogeneity in OFC procedures, particularly in cumulative dose, number, size, and timing between doses. Oral food challenge outcome reporting was often inadequate, especially regarding reaction symptoms and severity grading. In single-dose OFC protocols, most children reacted after at least 2 hours. Four small studies showed that a single dose of 25% of an age-appropriate portion was sufficient to trigger reactions in 80% to 100% of cases, and this was associated with less severe reactions. Owing to methodological heterogeneity and insufficient outcome reporting, further assessment of the OFC protocol characteristics associated with safer outcomes was not possible.

CONCLUSIONS

There is significant heterogeneity in FPIES OFC practices. Current recommendations for OFC procedures and outcome assessments have limitations and should be revisited, because this may affect patient safety and diagnostic accuracy. Future studies should focus on standardizing clinical outcomes and generating evidence to support safer, more accurate OFC protocols in FPIES.

Current status and future directions in food protein-induced enterocolitis syndrome: An NIAID workshop report of the June 22, 2022, virtual meeting

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal food allergy characterized by delayed, protracted vomiting and accompanied by lethargy and pallor, usually 1 to 4 hours after ingesting the food allergen. The pathophysiology of FPIES remains unknown, and currently there are no diagnostic biomarkers available to assess disease activity or its resolution. Over the last 2 decades, FPIES has become increasingly recognized in both pediatric and adult patients. Forty years after the initial FPIES description, the first FPIES code appeared in the International Classification of Diseases, Tenth Revision (ICD-10), and the first international consensus guidelines for the diagnosis and management of FPIES were published. On June 22, 2022, the National Institute of Allergy and Infectious Diseases (NIAID) held its first virtual multidisciplinary workshop on FPIES. Various clinical and translational aspects of FPIES as well as important areas of unmet needs were discussed as priorities for future research during this 2-day virtual workshop. Our report provides a summary of content of the workshop, including updated literature on the topic areas, and also provides critical commentary on the state of FPIES.

Whole Exome Sequencing Identifies Epithelial and Immune Dysfunction-Related Biomarkers in Food Protein-Induced Enterocolitis Syndrome

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a food allergy primarily affecting infants, often leading to vomiting and shock. Due to its poorly understood pathophysiology and lack of specific biomarkers, diagnosis is frequently delayed. Understanding FPIES genetics can shed light on disease susceptibility and pathophysiology-key to developing diagnostic, prognostic, preventive and therapeutic strategies. Using a well-characterised cohort of patients we explored the potential genome-wide susceptibility factors underlying FPIES.

METHODS

Blood samples from 41 patients with oral food challenge-proven FPIES were collected for a comprehensive whole exome sequencing association study.

RESULTS

Notable genetic variants, including rs872786 (RBM8A), rs2241880 (ATG16L1) and rs2289477 (ATG16L1), were identified as significant findings in FPIES. A weighted SKAT model identified six other associated genes including DGKZ and SIRPA. DGKZ induces TGF-β signalling, crucial for epithelial barrier integrity and IgA production; RBM8A is associated with thrombocytopenia absent radius syndrome, frequently associated with cow's milk allergy; SIRPA is associated with increased neutrophils/monocytes in inflamed tissues as often observed in FPIES; ATG16L1 is associated with inflammatory bowel disease. Coexpression correlation analysis revealed a functional correlation between RBM8A and filaggrin gene (FLG) in stomach and intestine tissue, with filaggrin being a known key pathogenic and risk factor for IgE-mediated food allergy. A transcriptome-wide association study suggested genetic variability in patients impacted gene expression of RBM8A (stomach and pancreas) and ATG16L1 (transverse colon).

CONCLUSIONS

This study represents the first case-control exome association study of FPIES patients and marks a crucial step towards unravelling genetic susceptibility factors underpinning the syndrome. Our findings highlight potential factors and pathways contributing to FPIES, including epithelial barrier dysfunction and immune dysregulation. While these results are novel, they are preliminary and need further validation in a second cohort of patients.

Contribution of T cell subsets to different food allergic diseases

Food allergies occur due to a lack of tolerance to the proteins found in foods. While IgE- and non-IgE-mediated food allergies have different clinical manifestations, epidemiology, pathophysiology, and management, they share dysregulated T cell responses. Recent studies have shed light on the contributions of different T cell subsets to the development and persistence of different food allergic diseases. This review discusses the role of T cells in both IgE- and non-IgE-mediated food allergies and considers the potential future investigations in this context.

Shift from Cow's Milk Food Protein-Induced Enterocolitis Syndrome to IgE-Mediated Allergy: Case Series and Literature Review

Background: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy characterized by gastrointestinal symptom onset within 1-4 hours from trigger food ingestion. In the literature, some authors have previously described the possibility that a patient with FPIES may develop an IgE-mediated allergy to the same trigger food, especially cow's milk (CM). Case Presentation: We reported five cases of CM-FPIES converting to IgE-mediated CM allergy presented at our tertiary pediatric Allergy Unit and performed a review of the literature, aiming to characterize the clinical features of patients who are at risk of developing such conversion. Conclusions: This phenomenon raises the question of whether IgE-mediated and non-IgE-mediated allergies represent a spectrum of the same disease and highlights the need for further investigation to understand the pathophysiological mechanisms of this process.

Heterogeneity of food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy with gastrointestinal symptoms such as vomiting and diarrhea. The development of international consensus guidelines for the diagnosis and management of FPIES in 2017 enabled us to compare patients worldwide, regardless of geographic variation in disease features. As a result, it has become clear that there is heterogeneity among patients with FPIES or that there are cases that partly fit the diagnostic criteria for FPIES but have different characteristics. This review highlights the heterogeneity in FPIES characteristics in terms of trigger foods, the age of onset, differences in geographic regions, and symptoms; it further proposes four disease entities, including acute FPIES in children, acute FPIES in adults, chronic FPIES, and early-onset neonatal FPIES, depending on the age of onset and presumed pathophysiology. The major symptoms at onset and trigger foods differ in acute FPIES in children, acute FPIES in adults, and chronic FPIES, whereas the disease entities may share a similar pathophysiology. Early-onset neonatal FPIES may have a different pathophysiology than acute or chronic FPIES, and may not necessarily fulfil the full diagnostic criteria for acute or chronic FPIES described in the international consensus guidelines. Due to the similarity in symptoms, early-onset neonatal FPIES may sometimes be misdiagnosed as necrotizing enterocolitis. We aim to increase awareness of FPIES among medical staff in pediatrics, neonatology, and internal medicine and promote research, to gain a better understanding of the heterogeneity and pathophysiology of FPIES.

Allergenic food protein consumption is associated with systemic IgG antibody responses in non-allergic individuals

Although food-directed immunoglobulin E (IgE) has been studied in the context of allergies, the prevalence and magnitude of IgG responses against dietary antigens are incompletely characterized in the general population. Here, we measured IgG binding against food and environmental antigens obtained from allergen databases and the immune epitope database (IEDB), represented in a phage displayed library of 58,233 peptides. By profiling blood samples of a large cohort representing the average adult Israeli population (n = 1,003), we showed that many food antigens elicited systemic IgG in up to 50% of individuals. Dietary intake of specific food protein correlated with antibody binding, suggesting that diet can shape the IgG epitope repertoire. Our work documents abundant systemic IgG responses against food antigens and provides a reference map of the exact immunogenic epitopes on a population scale, laying the foundation to unravel the role of food- and environmental antigen-directed antibody binding in disease contexts.

Update on Food Protein-Induced Enterocolitis Syndrome (FPIES)

PURPOSE OF REVIEW

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy characterized by delayed, and potentially severe, gastrointestinal symptoms. Since the advent of a specific diagnostic code and establishment of diagnostic guidelines, our understanding of this condition has grown.

RECENT FINDINGS

FPIES affects patients from early infancy into adulthood. Any food can be a trigger, and common culprit foods vary geographically and by age. An understanding of the complex underlying immune mechanisms remains elusive, although studies show pan-leukocyte activation, cytokine release, and increased gastrointestinal permeability. Management involves trigger avoidance, and patients may benefit from the support of a dietitian to ensure adequate nutrient intake. Tolerance develops over time for most children, but due to the risk of severe symptoms, re-introduction of a suspected FPIES trigger is recommended only under supervision at an oral food challenge. Studies continue to evaluate the optimal challenge protocol. Caregivers of children with FPIES report high levels of anxiety and stress, which is attributed to the dramatic symptomatology, dietary restrictions, nutritional concerns, lack of confirmatory diagnostic tests, and limited tools for management of reactions. Our understanding of the FPIES diagnosis has improved over the last few decades, but there remain opportunities, particularly regarding discerning the pathophysiology and best management practices.

Food Protein-Induced Enterocolitis Syndrome in Children with Down Syndrome: A Pilot Case-Control Study

Food protein-induced enterocolitis syndrome (FPIES) is a non-immunoglobin E-mediated food hypersensitivity disorder. However, little is known about the clinical features of FPIES in patients with Down syndrome (DS). Medical records of children with DS diagnosed at our hospital between 2000 and 2019 were retrospectively reviewed. Among the 43 children with DS, five (11.6%) were diagnosed with FPIES; all cases were severe. In the FPIES group, the median age at onset and tolerance was 84 days and 37.5 months, respectively. Causative foods were cow’s milk formula and wheat. The surgical history of colostomy was significantly higher in the FPIES group than in the non-FPIES group. A colostomy was performed in two children in the FPIES group, both of whom had the most severe symptoms of FPIES, including severe dehydration and metabolic acidosis. The surgical history of colostomy and postoperative nutrition of formula milk feeding may have led to the onset of FPIES. Therefore, an amino acid-based formula should be considered for children who undergo gastrointestinal surgeries, especially colostomy in neonates or early infants. When an acute gastrointestinal disease is suspected in children with DS, FPIES should be considered. This may prevent unnecessary tests and invasive treatments.

Pathophysiology of Non-IgE-Mediated Food Allergy

Non-IgE-mediated food allergies are a group of disorders characterized by subacute or chronic inflammatory processes in the gut. Unlike IgE mediated food allergies that may result in multi-organ system anaphylaxis, the non-IgE mediated food allergies primarily affect the gastrointestinal tract. This review outlines the clinical manifestations, epidemiology, pathophysiology, and management of non-IgE-mediated food allergies. An updated literature search of selected non-IgE-mediated food allergies was conducted for this review using PubMed database to the current year (2021). Reviewed disorders include food protein-induced enterocolitis syndrome (FPIES), food-protein enteropathy (FPE), food protein-induced allergic proctocolitis (FPIAP), and eosinophilic gastrointestinal disorders (EGIDs) such as eosinophilic esophagitis (EoE). While extensive gains have been made in understanding FPIES, FPIAP, FPE, and EoE, more information is needed on the pathophysiology of these food allergies. Similarities among them include involvement of innate immunity, T-lymphocyte processes, alteration of the intestinal lumen at the cellular level with the appearance of inflammatory cells and associated histologic changes, and specific cytokine profiles suggesting food-specific, T-cell, and immune-mediated responses. While FPIES and FPIAP typically resolve in early childhood, EGIDs typically do not. Emerging new therapies for EoE offer promise of additional treatment options. Further studies identifying the immunopathogenesis, associated biomarkers, and mechanisms of tolerance are needed to inform prevention, diagnosis and management.

Update on Food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE mediated food allergy (FA) characterized by delayed and severe gastrointestinal symptoms that typically occurs within the first year of life. Many aspects of this pathology are currently unclear. FPIES is classified as a non-IgE immune-mediated FA in which the immune response is thought to act mainly through cell-mediated mechanisms. In patients with FPIES, the symptom pattern is determined by the frequency and dose of food allergen in the diet. Diagnosis of FPIES may be difficult, mainly due to the lack of specific biomarkers to confirm or exclude the diagnosis. FPIES is a clinical diagnosis, mainly based on clinical features which, although not specific, are reproducible every time the patient takes the food. Different diagnostic criteria of FPIES were published over time in the literature. The present narrative review aims to analyze the current clinical evidence in epidemiology, pathophysiology, diagnosis, and management of this condition.

Natural immunomodulating substances used for alleviating food allergy

Food allergy is a serious health problem affecting more than 10% of the human population worldwide. Medical treatments for food allergy remain limited because immune therapy is risky and costly, and anti-allergic drugs have many harmful side effects and can cause drug dependence. In this paper, we review natural bioactive substances capable of alleviating food allergy. The sources of the anti-allergic substances reviewed include plants, animals, and microbes, and the types of substances include polysaccharides, oligosaccharides, polyphenols, phycocyanin, polyunsaturated fatty acids, flavonoids, terpenoids, quinones, alkaloids, phenylpropanoids, and probiotics. We describe five mechanisms involved in anti-allergic activities, including binding with epitopes located in allergens, affecting the gut microbiota, influencing intestinal epithelial cells, altering antigen presentation and T cell differentiation, and inhibiting the degranulation of effector cells. In the discussion, we present the limitations of existing researches as well as promising advances in the development of anti-allergic foods and/or immunomodulating food ingredients that can effectively prevent or alleviate food allergy. This review provides a reference for further research on anti-allergic materials and their hyposensitizing mechanisms.

Food Protein-Induced Enterocolitis Syndrome

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that manifests with projectile, repetitive emesis that can be followed by diarrhea and may be accompanied by lethargy, hypotonia, hypothermia, hypotension, and metabolic derangements. FPIES usually starts in infancy although onset at older ages is being increasingly recognized. FPIES is not rare, with the cumulative incidence of FPIES in infants estimated to be 0.015% to 0.7%, whereas the population prevalence in the US infants was 0.51%. FPIES diagnosis is challenging and might be missed because of later (1-4 hours) onset of symptoms after food ingestion, lack of typical allergic skin and respiratory symptoms, and food triggers that are perceived to be hypoallergenic. Diagnosis is based on the recognition of symptoms because there are no biomarkers of FPIES. The pathophysiology remains obscure although activation of the innate immune compartment has been detected. Management relies of avoidance of food triggers, treatment of accidental exposures, and periodic re-evaluations with supervised oral food challenges to monitor for resolution. There are no strategies to accelerate development of tolerance in FPIES. Here we review the most important current concepts in epidemiology, pathophysiology, diagnosis, and management of FPIES.

Food Allergy and Intolerance: A Narrative Review on Nutritional Concerns

Adverse food reactions include immune-mediated food allergies and non-immune-mediated intolerances. However, this distinction and the involvement of different pathogenetic mechanisms are often confused. Furthermore, there is a discrepancy between the perceived vs. actual prevalence of immune-mediated food allergies and non-immune reactions to food that are extremely common. The risk of an inappropriate approach to their correct identification can lead to inappropriate diets with severe nutritional deficiencies. This narrative review provides an outline of the pathophysiologic and clinical features of immune and non-immune adverse reactions to food-along with general diagnostic and therapeutic strategies. Special emphasis is placed on specific nutritional concerns for each of these conditions from the combined point of view of gastroenterology and immunology, in an attempt to offer a useful tool to practicing physicians in discriminating these diverging disease entities and planning their correct management. We conclude that a correct diagnostic approach and dietary control of both immune- and non-immune-mediated food-induced diseases might minimize the nutritional gaps in these patients, thus helping to improve their quality of life and reduce the economic costs of their management.

Food protein-induced enterocolitis syndrome: Dynamic relationship among gastrointestinal symptoms, immune response, and the autonomic nervous system

OBJECTIVE

To explore the relationship among gastrointestinal (GI) symptoms, immune response, and autonomic nervous system (ANS) in food protein-induced enterocolitis syndrome (FPIES) in relation to the current understanding of disease phenotype and pathogenesis.

DATA SOURCES

Relevant studies related to FPIES, GI symptomatology, and ANS were reviewed. Literature search was performed using PubMed, with keyword combinations including but not limited to FPIES, allergic GI disorders, ANS, autonomic dysfunction, dysautonomia, GI, diarrhea, vomiting, neuroimmune, and clinical phenotyping tools.

STUDY SELECTIONS

Peer-reviewed case-control studies, observational studies, reviews and guidelines, and systematic reviews related to FPIES and ANS were selected for review.

RESULTS

There is limited research directly relating GI symptoms and FPIES to the ANS and immunologic response. To support the proposed mechanisms of action related to patient symptoms, studies relevant to coexisting GI-autonomic processes and FPIES immunologic triggers were examined. These related disease processes were extrapolated to FPIES based on the current knowledge of FPIES phenotype and pathogenesis.

CONCLUSION

The etiology of FPIES and the underlying mechanisms triggering symptoms are not well understood. On the basis of the exaggerated GI symptoms and hemodynamic response observed, the ANS likely plays an important role in FPIES, possibly as a compensatory response. The trigger for this cascade of symptoms may be related to the disruption of immunologic homeostasis that typically contributes to immune tolerance. To more accurately evaluate FPIES pathophysiology necessitates understanding the diverse spectrum of presenting symptoms. A consistent and comprehensive symptom assessment tool may improve our understanding of this dynamic relationship.

Advances in understanding immune mechanisms of food protein-induced enterocolitis syndrome

OBJECTIVE

This review provides an overview of our current understanding of the mechanisms of food protein-induced enterocolitis syndrome (FPIES).

DATA SOURCES

To capture recent articles published since our previous comprehensive review on the pathophysiology of FPIES, we performed a literature search through PubMed database, using the search terms FPIES and food protein-induced enterocolitis syndrome from 2016 to the current year.

STUDY SELECTIONS

Studies in English containing biomarker or immune data were reviewed and summarized.

RESULTS

Studies of peripheral blood fail to exhibit evidence of antigen-specific humoral or cellular immunity underlying clinical reactivity to foods in FPIES. However, growing evidence suggests a robust systemic innate immune activation occurring during FPIES reactions and the activation of neuroendocrine pathways.

CONCLUSION

FPIES reactions are associated with marked activation of innate immune and neuroendocrine pathways; however, the mechanism underlying the specific recognition of foods remains elusive.

Management of acute food protein-induced enterocolitis syndrome emergencies at home and in a medical facility

OBJECTIVE

Acute food protein-induced enterocolitis syndrome (FPIES) is characterized by delayed repetitive vomiting after ingestion of a trigger food, and severe reactions may lead to dehydration, hypotension, and shock. We provide recommendations on management of FPIES emergencies in a medical facility and at home.

DATA SOURCES

This review summarizes the literature on clinical context, pathophysiology, presentation, and treatment of FPIES emergencies.

STUDY SELECTIONS

We referred to the 2017 International Consensus Guidelines for the Diagnosis and Management of FPIES and performed a literature search identifying relevant recent primary articles and review articles on clinical management.

RESULTS

Management of FPIES emergencies in a medical facility is based on severity of symptoms and involves rehydration, ondansetron, and corticosteroids. A proactive approach for reactions occurring at home involves prescribing oral ondansetron and providing an individualized treatment plan based on the evolution of symptoms and severity of past reactions. A better understanding of the pathophysiology of FPIES and randomized trials on ondansedron and cocorticosteroid use could lead to more targeted treatments.

CONCLUSION

Children with FPIES are at risk for severe symptoms constituting a medical emergency. Management of FPIES emergencies is largely supportive, with treatment tailored to the symptoms, severity of the patient's condition, location of reaction, and reaction history.

Divergent T follicular helper cell requirement for IgA and IgE production to peanut during allergic sensitization

Immunoglobulin A (IgA) is the dominant antibody isotype in the gut and has been shown to regulate microbiota. Mucosal IgA is also widely believed to prevent food allergens from penetrating the gut lining. Even though recent work has elucidated how bacteria-reactive IgA is induced, little is known about how IgA to food antigens is regulated. Although IgA is presumed to be induced in a healthy gut at steady state via dietary exposure, our data do not support this premise. We found that daily food exposure only induced low-level, cross-reactive IgA in a minority of mice. In contrast, induction of significant levels of peanut-specific IgA strictly required a mucosal adjuvant. Although induction of peanut-specific IgA required T cells and CD40L, it was T follicular helper (T_FH) cell, germinal center, and T follicular regulatory (T_FR) cell-independent. In contrast, IgG1 and IgE production to peanut required T_FH cells. These data suggest an alternative paradigm in which the cellular mechanism of IgA production to food antigens is distinct from IgE and IgG1. We developed an equivalent assay to study this process in stool samples from healthy, nonallergic humans, which revealed substantial levels of peanut-specific IgA that were stable over time. Similar to mice, patients with loss of CD40L function had impaired titers of gut peanut-specific IgA. This work challenges two widely believed but untested paradigms about antibody production to dietary antigens: (i) the steady state/tolerogenic response to food antigens includes IgA production and (ii) T_FH cells drive food-specific gut IgA.

Expression of Leucine-rich Repeat-containing Protein 32 Following Lymphocyte Stimulation in Patients with Non-IgE-mediated Gastrointestinal Food Allergies

The lymphocyte stimulation test (LST) facilitates the diagnosis of non-IgE-mediated gastrointestinal food allergies (non-IgE-GI-FAs). However, LSTs require large volumes of blood and prolonged culture durations. Recently, we found that IL2RA mRNA expression in peripheral blood mononuclear cells (PBMCs) of patients with non-IgE-GI-FAs increased after a 24 h stimulation with milk proteins. We designated this gene expression test as the instant peripheral blood allergen stimulation test (iPAST). In this study, we investigated whether other activated T cell-associated genes are superior to IL2RA in the iPAST for the supplementary diagnosis of non-IgE-GI-FAs. After incubating PBMCs with milk proteins for 24 h, the mRNA levels of three genes, LRRC32, TNFRSF4, and CD69, were assessed using quantitative RT-PCR. The diagnostic significance of the mRNA expression was evaluated by analyzing the receiver operating characteristic (ROC) curve. Upon stimulation with α-casein, κ-casein, α-lactalbumin, or a mixture of four milk protein components (Pmix), LRRC32 expression in the PBMCs of 16 patients with non-IgE-GI-FAs was found to be higher than that in their 17 control counterparts, whereas TNFRSF4 and CD69 levels remained unaltered. Except for β-lactoglobulin and cow's milk (CM), the area under the ROC curve (AUC) for LRRC32 mRNA expression upon stimulation was >0.7, which validated the diagnostic ability of this test. Notably, α-casein and Pmix had higher AUC scores of 0.820 and 0.842, respectively, than other antigens. iPAST assessed by LRRC32 as well as IL2RA may be useful for the supplementary diagnosis of non-IgE-GI-FAs as an alternative to LSTs and provide insight into the pathogenesis of non-IgE-GI-FAs.

Dietary Soy Protein Isolate Attenuates Intestinal Immunoglobulin and Mucin Expression in Young Mice Compared with Casein

Dietary protein sources have profound effects on children and young animals, and are important for the gut barrier function and immune resilience. Milk and soy are the main sources of protein for children and young animals after weaning. The objective of this study was to compare the effects of dairy and soy proteins on the intestinal barrier in early development. Weanling C57BL/6 mice were fed AIN-93G diets prepared with casein or soy protein isolate (SPI) for 21 days. Compared with those fed with the casein diet, mice fed with the SPI diet did not change their body weight and organ coefficients, but increased their feed intake and ratio of feed to gain. SPI lowered the level of luminal secretory immunoglobulin A (SIgA) and downregulated the levels of IL-4, IL-13, polymeric immunoglobulin receptor (Pigr), Janus kinase 1 (Jak1), signal transducer and activator of transcription 6 (Stat6), and transforming growth factor-β (Tgfb) in the mouse ileum. Western blotting of ileal proteins confirmed that SPI suppressed the activation of the JAK1/STAT6 signaling pathway. Furthermore, SPI attenuated intestinal mucin production, as demonstrated by the decreased numbers of intestinal goblet cells and the reduced relative expression levels of mucin 1 (Muc1), mucin 2 (Muc2), trefoil factor 3 (Tff3), glucose-regulated protein 94 (Grp94), and anterior gradient homolog 2 (Agr2). The results indicated that the SPI diet could attenuate mouse intestinal immunity, as demonstrated by decreased SIgA and mucin production in the intestine. Therefore, we suggest that our findings should be of consideration when SPI or casein are used as dietary protein sources.

Non-IgE-Mediated Gastrointestinal Food Allergies in Children: An Update

Non-immunoglobulin E-mediated gastrointestinal food allergic disorders (non-IgE-GI-FA) include food protein-induced enterocolitis syndrome (FPIES), food protein-induced enteropathy (FPE) and food protein-induced allergic proctocolitis (FPIAP), which present with symptoms of variable severity, affecting the gastrointestinal tract in response to specific dietary antigens. The diagnosis of non-IgE-GI-FA is made clinically, and relies on a constellation of typical symptoms that improve upon removal of the culprit food. When possible, food reintroduction should be attempted, with the documentation of symptoms relapse to establish a conclusive diagnosis. Management includes dietary avoidance, nutritional counselling, and supportive measures in the case of accidental exposure. The prognosis is generally favorable, with the majority of cases resolved before school age. Serial follow-up to establish whether the acquisition of tolerance has occurred is therefore essential in order to avoid unnecessary food restriction and potential consequent nutritional deficiencies. The purpose of this review is to delineate the distinctive clinical features of non-IgE-mediated food allergies presenting with gastrointestinal symptomatology, to summarize our current understanding of the pathogenesis driving these diseases, to discuss recent findings, and to address currents gaps in the knowledge, to guide future management opportunities.

Genome-Wide Association Study for Milk Protein Composition Traits in a Chinese Holstein Population Using a Single-Step Approach

Genome-wide association studies (GWASs) have been widely used to determine the genetic architecture of quantitative traits in dairy cattle. In this study, with the aim of identifying candidate genes that affect milk protein composition traits, we conducted a GWAS for nine such traits (α_s1-casein, α_s2-casein, β-casein, κ-casein, α-lactalbumin, β-lactoglobulin, casein index, protein percentage, and protein yield) in 614 Chinese Holstein cows using a single-step strategy. We used the Illumina BovineSNP50 Bead chip and imputed genotypes from high-density single-nucleotide polymorphisms (SNPs) ranging from 50 to 777 K, and subsequent to genotype imputation and quality control, we screened a total of 586,304 informative high-quality SNPs. Phenotypic observations for six major milk proteins (α_s1-casein, α_s2-casein, β-casein, κ-casein, α-lactalbumin, and β-lactoglobulin) were evaluated as weight proportions of the total protein fraction (wt/wt%) using a commercial enzyme-linked immunosorbent assay kit. Informative windows comprising five adjacent SNPs explaining no < 0.5% of the genomic variance per window were selected for gene annotation and gene network and pathway analyses. Gene network analysis performed using the STRING Genomics 10.0 database revealed a co-expression network comprising 46 interactions among 62 of the most plausible candidate genes. A total of 178 genomic windows and 194 SNPs on 24 bovine autosomes were significantly associated with milk protein composition or protein percentage. Regions affecting milk protein composition traits were mainly observed on chromosomes BTA 1, 6, 11, 13, 14, and 18. Of these, several windows were close to or within the CSN1S1, CSN1S2, CSN2, CSN3, LAP3, DGAT1, RPL8, and HSF1 genes, which have well-known effects on milk protein composition traits of dairy cattle. Taken together with previously reported quantitative trait loci and the biological functions of the identified genes, we propose 19 novel candidate genes affecting milk protein composition traits: ARL6, SST, EHHADH, PCDHB4, PCDHB6, PCDHB7, PCDHB16, SLC36A2, GALNT14, FPGS, LARP4B, IDI1, COG4, FUK, WDR62, CLIP3, SLC25A21, IL5RA, and ACADSB. Our findings provide important insights into milk protein synthesis and indicate potential targets for improving milk quality.

Deep analysis of immune response and metabolic signature in children with food protein induced enterocolitis to cow's milk

Background

Food Protein-Induced Enterocolitis Syndrome (FPIES) is considered to be a non-IgE mediated food allergy. However, its pathogenesis remains poorly understood and biomarkers are lacking. We aimed to perform in-depth characterization of humoral and cellular immune responses in children with cow’s milk (CM)-FPIES and investigated whether there is a FPIES metabolomic signature.

Methods

Children with CM-FPIES and control subjects with an IgE-mediated CM allergy (IgE-CMA), both avoiding CM, were recruited on the day of an oral food challenge. Blood samples were collected before the challenge. Total and specific levels of IgE, IgG1-4, IgA, IgM and IgD to various whey and casein allergens and to their gastroduodenal digestion products were measured in plasma, using plasma from CM-tolerant peanut allergic patients (IgE-PA, not avoiding CM) as additional controls. Cytokine secretion and cellular proliferation were analyzed after stimulation of PBMC with different CM allergens. Metabolomic profiles were obtained for plasma samples using liquid chromatography coupled to high-resolution mass spectrometry.

Results

Nine children with CM-FPIES and 12 control subjects (6 IgE-CMA and 6 IgE-PA) were included. In children with CM-FPIES, total Ig concentrations were lower than in control subjects, specific Ig against CM components were weak to undetectable, and no specific IgE against CM digestion products were detected. Moreover, in CM-FPIES patients, we did not find any Th cell proliferation or associated cytokine secretion after allergen reactivation, whereas such responses were clearly found in children with IgE-CMA. Plasma metabolic profiles were different between CM allergic patients, with significantly lower concentrations of various fatty acids and higher concentrations of primary metabolites such as amino acids in CM-FPIES compared to IgE-CMA patients.

Conclusions

In CM-FPIES, both humoral and cellular specific immune responses are weak or absent, and this is not related to CM avoidance. A metabolomic signature was identified in patients with CM-FPIES that may be useful for the diagnosis and management of this disease.

Electronic supplementary material

The online version of this article (10.1186/s13601-018-0224-9) contains supplementary material, which is available to authorized users.

Non-IgE-mediated Adverse Food Reactions

PURPOSE OF REVIEW

The purpose of this review is to update what is currently known about the major non-IgE-mediated food allergies: food protein-induced enterocolitis syndrome (FPIES), food protein-induced allergic proctocolitis (FPIAP), and food protein-induced enteropathy (FPE). These conditions are similar in that symptoms are regulated to the gastrointestinal tract; therefore understanding their specific features is important for diagnosis and management.

RECENT FINDINGS

The most progress has been made in understanding FPIES with several recent large cohorts being described. The first international consensus guidelines for FPIES were published in 2017 and propose specific diagnostic criteria for acute FPIES as well as guidance for diagnosing chronic FPIES. Recent studies in FPIAP have challenged our thinking about the recommended duration of food avoidance and that cow's milk avoidance is the primary management with reports of self-resolution without dietary management. FPE continues to appear to be on the decline. FPIES, FPIAP, and FPE are distinguished from one another by their main clinical features: delayed repetitive vomiting in FPIES, benign blood in stool in FPIAP, and chronic diarrhea in FPE. Due to the risk of nutritional deficiencies with food avoidance in both infant and maternal diets if breastfeeding, confirmation of diagnosis with challenges is encouraged. Additional studies are needed for these conditions to elucidate pathophysiology, search for diagnostic markers, and understand natural history.

A systematic review of food protein-induced enterocolitis syndrome from the last 40 years

OBJECTIVE

To provide a complete, exhaustive summary of current literature relevant to food protein-induced enterocolitis syndrome (FPIES).

DATA SOURCES

Data have been extracted from PubMed and Science Direct databases.

STUDY SELECTIONS

Following the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines, a literature search for peer-reviewed journal articles in English through January 1975 with updates through October 2016 was conducted. Relevant publications were reviewed that included pediatric and adult populations. Information on the study design, sample, intervention, comparators, outcome, timeframe, and risk of bias were abstracted for each article.

RESULTS

Of 135 reviewed reports, 52 were included in this systematic review. In accordance with the age at onset, clinical features, and offending foods, it is possible to distiguish different types of FPIES. An immune systemic involvement can occur in patients with FPIES. In addition to the most common causative foods (cow's milk, soy, and rice), any food can potentially cause FPIES. Although specific diagnostic tests are not available, open food challenge remains the gold standard for FPIES diagnosis. Moreover, because of the lack of randomized clinical trials and of use of different adopted methods, confounding factors might mask critical findings, leading to poor knowledge of this pleiotropic clinical entity.

CONCLUSION

Multicenter studies are needed to better develop an evidence-based approach to pathophysiology, prevalence, diagnosis, and natural history of the disease.

Systemic innate immune activation in food protein-induced enterocolitis syndrome

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy of infancy whose pathophysiology is poorly understood.

OBJECTIVES

We set out to identify and phenotype allergen-responsive cells in peripheral blood of a cohort of subjects undergoing supervised food challenge for FPIES.

METHODS

We profiled antigen-responsive cells in PBMCs by flow cytometry, and examined cells in whole blood obtained before and after challenge by CyTOF mass cytometry and RNAseq.

RESULTS

Using a CD154-based detection approach, we observed that milk, soy, or rice-responsive T cells, and TNF-α-producing CD154⁺ T cells, were significantly lower in those with outgrown FPIES compared with those with active FPIES. However, levels were within the normal range and were inconsistent with a role in the pathophysiology of FPIES. Profiling of whole blood by CyTOF demonstrated profound activation of cells of the innate immune system after food challenge, including monocytes, neutrophils, natural killer cells, and eosinophils. Activation was not observed in children with outgrown FPIES. We confirmed this pattern of innate immune activation in a larger cohort by RNAseq. Furthermore, we observed pan-T-cell activation and redistribution from the circulation after a positive food challenge but not in those who had outgrown their FPIES.

CONCLUSIONS

Our data demonstrate a compelling role of systemic innate immune activation in adverse reactions elicited by foods in FPIES. Further investigation is needed to identify the mechanism of antigen specificity of adverse reactions to foods in FPIES.

Non-IgE-mediated gastrointestinal food allergies in children

Non-IgE-mediated gastrointestinal food allergic disorders (non-IgE-GI-FA) including food protein-induced enterocolitis syndrome (FPIES), food protein-induced enteropathy (FPE), and food protein-induced allergic proctocolitis (FPIAP) are relatively uncommon in infants and young children, but are likely under-diagnosed. Non-IgE-GI-FA have a favorable prognosis, with majority resolving by age 3-5 years. Diagnosis relies on the recognition of symptoms pattern in FPIAP and FPIES and biopsy in FPE. Further studies are needed for a better understanding of the pathomechanism, which will lead eventually to the development of diagnostic tests and treatments. Limited evidence supports the role of food allergens in subsets of constipation, gastroesophageal reflux disease, irritable bowel syndrome, and colic. The immunologic pathomechanism is not fully understood and empiric prolonged avoidance of food allergens should be limited to minimize nutrient deficiency and feeding disorders/food aversions in infants.

Food protein-induced enterocolitis syndrome - a review of the literature with focus on clinical management

Food protein-induced enterocolitis syndrome (FPIES) is a potentially severe presentation of non-IgE-mediated gastrointestinal food allergy (non-IgE-GI-FA) with heterogeneous clinical manifestations. Acute FPIES is typically characterized by profuse vomiting and lethargy, occurring classically 1-4 hours after ingestion of the offending food. When continuously exposed to the incriminated food, a chronic form has been described with persistent vomiting, diarrhea, and/or failure to thrive. Although affecting mainly infants, FPIES has also been described in adults. Although FPIES is actually one of the most actively studied non-IgE-GI-FAs, epidemiologic data are lacking, and estimation of the prevalence is based on a limited number of prospective studies. The exact pathomechanisms of FPIES remain not well defined, but recent data suggest involvement of neutrophils and mast cells, in addition to T cells. There is a wide range of food allergens that can cause FPIES with some geographical variations. The most frequently incriminated foods are cow milk, soy, and grains in Europe and USA. Furthermore, FPIES can be induced by foods usually considered as hypoallergenic, such as chicken, potatoes or rice. The diagnosis relies currently on typical clinical manifestations, resolving after the elimination of the offending food from the infant's/child's diet and/or an oral food challenge (OFC). The prognosis is usually favorable, with the vast majority of the case resolving before 5 years of age. Usually, assessment of tolerance acquisition by OFC is proposed every 12-18 months. Of note, a switch to an IgE-mediated FA is possible and has been suggested to be associated with a more severe phenotype. Avoiding the offending food requires education of the family of the affected child. A multidisciplinary approach including ideally allergists, gastroenterologists, dieticians, specialized nurses, and caregivers is often useful to optimize the management of these patients, that might be difficult.

The epithelial barrier and immunoglobulin A system in allergy

Airway and intestinal epithelial layers represent first-line physical barriers, playing a key role in mucosal immunity. Barrier dysfunction, characterized by alterations such as disruption of cell-cell apical junctions and aberrant epithelial responses, probably constitutes early and key events for chronic immune responses to environmental antigens in the skin and in the gut. For instance, barrier dysfunction drives Th2 responses in atopic disorders or eosinophilic esophagitis. Such epithelial impairment is also a salient feature of allergic asthma and growing evidence indicates that barrier alterations probably play a driving role in this disease. IgA has been identified as the most abundant immunoglobulin in mucosa, where it acts as an active barrier through immune exclusion of inhaled or ingested antigens or pathogens. Historically, it has been thought to represent the serum factor underlying reaginic activity before IgE was discovered. Despite several studies about regulation and major functions of IgA at mucosal surfaces, its role in allergy remains largely unclear. This review aims at summarizing findings about epithelial functions and IgA biology that are relevant to allergy, and to integrate the emerging concepts and the recent developments in mucosal immunology, and how these could translate to clinical observations in allergy.

Clinical and immunological characteristics of a pediatric population with food protein-induced enterocolitis syndrome (FPIES) to fish

BACKGROUND

Food protein-induced enterocolitis (FPIES) is an uncommon, non-IgE-mediated food allergy that usually debuts in infancy with profuse vomiting, lethargy, and pallor 2-4 h following ingestion of the offending food. Its immune mechanism is not known. We aimed to describe the clinical features and outcome of children with fish-FPIES as well as to investigate on cellular immune response implicated.

METHODS

Prospective and follow-up clinical study of children with FPIES by fish over a period between 2004 and 2013 was conducted. Measurement in vitro of both cytokine production in peripheral blood mononuclear cells (PBMCs) and expression of HLA-DR in monocyte-derived dendritic cells stimulated with fish extracts.

RESULTS

Sixteen children (seven male and nine female) were included, with a mean age of onset at 10 months. Diagnosis was established after a median of 4 reactions. Twelve patients were treated in emergency room, and two were admitted in intensive care. Patch tests were positive in six patients. Skin prick tests (SPTs) and specific IgE to all fish tested were negative. Only three children reached tolerance at a mean age of 4.5 years. Eight children avoided fish because of positive oral food challenge (OFC) after 6 years of age. Other patients have not been challenged because of parent refusal to OFC or a recent diagnosis. TNF-α was increased in patients, and a significant elevation of the HLA-DR marker was also observed in these patients vs. control donors.

CONCLUSIONS

FPIES caused by fish in many cases presents with severe clinical manifestations. Patch test has poor diagnostic value, and OFC is the gold standard to test tolerance. The cytokine TNF-α may be implicated in the clinical symptoms. Higher expression of HLA-DR in dendritic cells has also been detected in our patients.

Allergen extracts for immunotherapy: to mix or not to mix?

Allergen immunotherapy (AIT) is established as a curative treatment for allergic rhinitis, asthma, as well as insect venom allergy. AIT is based on the administration of natural allergen extracts via the subcutaneous or sublingual routes to reorient the immune system towards tolerogenic mechanisms. In this regard, since many patients are poly-allergic, mixtures of allergen extracts are often used with a potential risk to cause allergen degradation, thereby affecting treatment efficacy. Herein, we discuss the advantages and drawbacks of mixing homologous (i.e., related) or heterogeneous (i.e., unrelated) allergen extracts. We provide evidence for incompatibilities between mixes of grass pollen and house dust mite extracts containing bodies and feces, and summarize critical points to consider when mixing allergen extracts for AIT.

Milk metabolites and neurodegeneration: Is there crosstalk?

Milk has been considered as a natural source of nutrition for decades. Milk is known to be nutrient-rich which aids the growth and development of the human body. Milk contains both macro- and micronutrients. Breast milk is widely regarded as the optimal source of neonatal nutrition due to its composition of carbohydrates, proteins, minerals and antibodies. However, despite the wide use of milk products, investigations into the role of milk in degenerative diseases have been limited. This review will examine the relationship between the β-casein gene found in bovine milk and disease states by using age-related macular degeneration as an example.

Food Protein-Induced Enterocolitis Syndrome, Allergic Proctocolitis, and Enteropathy

Food protein-induced enterocolitis (FPIES), allergic proctocolitis (FPIAP), and enteropathy (FPE) are among a number of immune-mediated reactions to food that are thought to occur primarily via non-IgE-mediated pathways. All three are typically present in infancy and are triggered most commonly by cow's milk protein. The usual presenting features are vomiting with lethargy and dehydration in FPIES; bloody and mucous stools in FPIAP; and diarrhea with malabsorption and failure to thrive in FPE. Diagnosis is based on convincing history and resolution of symptoms with food avoidance; confirmatory diagnostic testing other than food challenge is lacking. The mainstay of management is avoidance of the suspected inciting food, with interval challenge to assess for resolution, which usually occurs in the first years of life. Studies published in the past few years clarify common presenting features, report additional culprit foods, address potential biomarkers, and suggest new management strategies.

Non-IgE-mediated gastrointestinal food allergy

Non-IgE-mediated gastrointestinal food-induced allergic disorders (non-IgE-GI-FAs) account for an unknown proportion of food allergies and include food protein-induced enterocolitis syndrome (FPIES), food protein-induced allergic proctocolitis (FPIAP), and food protein-induced enteropathy (FPE). Non-IgE-GI-FAs are separate clinical entities but have many overlapping clinical and histologic features among themselves and with eosinophilic gastroenteropathies. Over the past decade, FPIES has emerged as the most actively studied non-IgE-GI-FA, potentially because of acute and distinct clinical features. FPIAP remains among the common causes of rectal bleeding in infants, while classic infantile FPE is rarely diagnosed. The overall most common allergens are cow's milk and soy; in patients with FPIES, rice and oat are also common. The most prominent clinical features of FPIES are repetitive emesis, pallor, and lethargy; chronic FPIES can lead to failure to thrive. FPIAP manifests with bloody stools in well-appearing young breast-fed or formula-fed infants. Features of FPE are nonbloody diarrhea, malabsorption, protein-losing enteropathy, hypoalbuminemia, and failure to thrive. Non-IgE-GI-FAs have a favorable prognosis; the majority resolve by 1 year in patients with FPIAP, 1 to 3 years in patients with FPE, and 1 to 5 years in patients with FPIES, with significant differences regarding specific foods. There is an urgent need to better define the natural history of FPIES and the pathophysiology of non-IgE-GI-FAs to develop biomarkers and novel therapies.

Immunopathophysiology of food protein-induced enterocolitis syndrome

There is increasing recognition of the non-IgE-mediated gastrointestinal food allergy known as food protein-induced enterocolitis syndrome (FPIES), with several recent publications summarizing the clinical experience with FPIES in the United States, the United Kingdom, Europe, and Australia. Our understanding of the mechanisms linking food exposure to typical symptoms of vomiting, hypotension, and diarrhea has lagged far behind our understanding of the immune mechanisms of IgE-mediated food allergy. The goal of this overview is to summarize and critique the current state of knowledge of the immunology of FPIES and to identify major gaps in our knowledge that need to be addressed to make significant gains in developing therapies and prevention strategies for FPIES.