Systemic innate immune activation in food protein-induced enterocolitis syndrome

The Immunological Mechanisms Involved in the Pathophysiology of Allergic Proctocolitis

BACKGROUND

The pathophysiology of non-IgE-mediated cow's milk allergy is mostly unknown. Previous studies suggested a mechanism mediated by T cells, but this was not confirmed in subsequent studies. The aim of this study was to investigate the immunological mechanisms, especially the role of regulatory T cells (Tregs), in the pathophysiology of allergic proctocolitis (FPIAP).

METHODS

A prospective observational study was conducted on infants with FPIAP and a control group of healthy infants with similar ages. The main variables were lymphocyte populations, included Tregs, which were extracted from peripheral blood and processed immediately by flow cytometry at two time points: in the acute phase ("T0") and after clinical resolution ("Tres").

RESULTS

A total of 32 patients with FPIAP and 10 healthy infants were enrolled. There was a higher T-CD4 memory cell count, increased numbers of regulatory B cells and a higher percentage of Tregs (p < 0.01) in patients with acute FPIAP in contrast to the healthy group. The levels of granulocytes (mainly eosinophils), dendritic cells (mDC2) and NK16+56- cells were also significantly higher in the FPIAP group. NK16+56- cells and the number of granulocytes appeared to be the best markers for distinguishing between the healthy and FPIAP infants based on the ROC curves.

CONCLUSIONS

FPIAP does not appear to have an immune mechanism mediated by T cells, but it may be associated with innate immunity responses characterized by an increase in NK16+56- cells, eosinophils and dendritic cells. These cells could be evaluated in future studies as possible markers of non-IgE-mediated cow's milk protein allergy.

Association of myeloid cell reactivity patterns with safe food predictions in FPIES patients

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is an understudied non-IgE-mediated food allergy, which is distinct from and lacks diagnostic testing akin to IgE testing. FPIES affects infants and toddlers but can persist into adulthood. As there are no extant methods to identify safe foods for FPIES patients, food ingestion trials are performed at home and often lead to reactions and development of food aversions, which may lead to failure-to-thrive and gastric feeding tube requirements. We hypothesized that foods that fail to elicit responses in immune cells of FPIES patients would be safe to ingest, which could support development of a diagnostic method to headstart safe food identification in patients.

METHODS

We developed an ex vivo model of FPIES using food-stimulated white blood cells (WBCs) from pediatric FPIES patients and controls by defining a 9-gene panel representative of FPIES ex vivo responses and conducted a single-arm pilot clinical trial.

RESULTS

Myeloid cells of FPIES patients displayed variable individual-specific myeloid cell reactivity patterns (iMCRPs) to different foods. Foods that failed to elicit repsonses in patients' immune cells were safe to ingest with a negative predictive value of 98.5%. This, when utilized in prospective predictions, reduced newly introduced food reaction rates from 19.5 to 0% while increasing food repertoire diversity.

CONCLUSIONS

iMCRPs represent a novel and potentially useful tool that associates with safe food ingestion in FPIES patients for foods that fail to elicit immune cell reactions. Trial Registration The trial has been registered at registered at ClinicalTrials.gov # NCT04644783.

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.

Food allergy endotypes revisited

In the last century, food allergy has become recognized as an increasingly prevalent and heterogeneous condition. Advances in biomedical technology have revealed complex genetic, environmental, immune, and metabolic pathways underlying the pathogenesis of food-allergic disorders. These findings permit classification of distinct food allergy endotypes with unique pathophysiologic features. In this review, we suggest that these endotypes of food-allergic disorders should be defined on the basis of (1) whether or not the allergic antibody IgE plays an essential role in disease pathogenesis, (2) the molecular features of the allergen (protein vs carbohydrate), and (3) the molecular markers associated with prognosis, severity, or clinical presentation. Beyond these broad categories, additional subtypes with unique mechanistic characteristics are discussed.

Neonatal Food Protein-Induced Enterocolitis: Current Insights and Knowledge Gaps

Acute and chronic Food Protein-Induced Enterocolitis Syndrome (FPIES) has been well characterized in children; otherwise, neonatal FPIES (N-FPIES) remains poorly understood. In terms of pathophysiology, neonatal FPIES appears to have a more prevalent TH2 response and is characterized by specific clinical features that make the diagnosis challenging. Genetic and environmental risk factors may predispose to the development of FPIES. Recent evidence indicates that a characteristic microbiota signature may lead to barrier dysfunction, reduced regulatory T cells, and abnormal intestinal production of serotonin, responsible for the symptoms of FPIES. Regarding clinical presentation, newborns with FPIES may not fully meet the current guideline's diagnostic criteria at disease onset, being more similar to clinical entity specific of neonatal age than to acute FPIES in infants and children. Hence, differentiation from other neonatal medical and surgical conditions-particularly necrotizing enterocolitis (NEC)-remains a critical challenge for clinicians. This present review highlights our current understanding of N-FPIES, in term of pathophysiology, clinical presentation diagnosis, and treatment strategies. Refining diagnostic criteria for N-FPIES represents a clinical priority to help physicians in diagnosing and managing this challenging condition. Last, but not least, larger clinical trials are needed to optimize treatment practices in term and preterm newborns with FPIES.

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.

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.

The role of neutrophils in allergic disease

Neutrophils are short-lived cells of the innate immune system and represent 50-70% of the circulating leucocytes. Their primary role is antimicrobial defence which they accomplish through rapid migration to sites of inflammation followed by phagocytosis, degranulation, and the release of neutrophil extracellular traps (NETosis). While previously considered terminally differentiated cells, they have been shown to have great adaptability and to play a role in conditions ranging from cancer to autoimmunity. This review focuses on their role in allergic disease. In particular: their role as potential amplifiers of type 1 hypersensitivity reactions leading to anaphylaxis; their involvement in alternative pathways of food and drug allergy; their role in allergic rhinitis and asthma and neutrophil dysfunction in atopic dermatitis. The use of potential biomarkers and therapeutic targets is also discussed with a view to guiding future research.

Immunoglobulin-coating patterns reveal altered humoral responses to gut bacteria in pediatric cow milk allergies

BACKGROUND

Pediatric cow milk allergies (CMA) can occur in immunoglobulin (Ig) E and non-IgE-mediated forms. Unlike IgE-mediated allergies, the mechanisms of disease pathogenesis in non-IgE-mediated food allergy and an association with microbiome has not been well established. Previous studies have identified the presence of altered humoral responses to gut bacteria in IgE mediated allergies. Here, we analyzed IgA, IgE and IgG responses to gut bacteria in subjects with either IgE or non-IgE mediated CMA to identify relative proportions of Ig-coated bacteria and characterize unique disease specific microbial signatures.

METHODS

Multi-parametric flow cytometry analysis was used to identify IgA, IgE and IgG responses to gut bacteria in CMA patients. Cell sorting of Ig coated gut bacteria was subsequently performed followed by high throughput 16S rRNA gene sequencing and specific patterns of humoral responses to gut bacteria assessed in each study group.

RESULTS

We identified significant alterations in IgA and IgG gut bacterial coating patterns in CMA subjects. Proportions of IgA-coated bacteria were decreased in IgE mediated CMA subjects without atopic dermatitis (ALL) and non-IgE mediated CMA subjects (ENP), compared to healthy controls (CON). In comparison, IgG-coated bacteria was significantly elevated in CMA subjects with atopic dermatitis (AD). Alpha and beta diversities displayed significant differences in IgA-, IgE-, and IgG-coated bacteria in AD and ENP groups. Significant differences in bacteria coated by IgA, IgE and IgG were detected at Phyla, Genus and Species levels and associated bacterial dysbiosis in IgE and non-IgE mediated allergies were identified. Linear discriminant analysis (LDA) effect size (LEFse) revealed unique disease associated bacterial signatures, including several pathogenic bacteria namely Bacteroides fragilis, Ruminococcus gnavus, Eubacterium dolichum, Fusobacterium, Clostridium neonatale and Robinsoniella peoriensis. Receiver operating characteristic curve analysis confirmed the efficiency of using the bacterial signatures identified as biomarkers for disease.

CONCLUSIONS

Altered IgA and IgG responses to gut bacteria were identified in CMA subjects. The disease-specific responses were associated with alterations in bacterial diversity and concomitant dysbiosis of Ig-coated bacteria in IgE-mediated and non-IgE-mediated CMA pediatric subjects. The identification of pathogenic bacteria uniquely associated with different classes of allergic disease indicates a role of these bacteria in driving disease-specific pathological phenotypes.

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.

Clinical-Hematological Changes and Predictors of Severity in Acute Food Protein-Induced Enterocolitis Syndrome Reactions at Oral Food Challenge: A Multicenter Observational Study

BACKGROUND

Oral food challenge (OFC) is the criterion standard for diagnosis of acute food protein-induced enterocolitis syndrome (FPIES). No diagnostic/prognostic biomarkers are available, and OFC assessment criteria are not validated.

OBJECTIVE

To assess clinical-hematological changes and predictors of severity of FPIES reactions at OFC.

METHODS

This was an observational multicenter prospective study. Children aged 0 to 18 years diagnosed with acute FPIES were recruited at follow-up OFC in 12 tertiary centers in Spain and Italy. OFC outcomes (as positive/negative/inconclusive and mild/moderate/severe) were assessed on the basis of published "2017 FPIES Consensus" criteria. Clinical characteristics were recorded, and full blood cell count was done at baseline, reaction onset, and 4 hours later. Regression analysis was performed to assess predictors of severe reactions at OFC.

RESULTS

A total of 81 children had positive OFC (mild in 11% [9 of 81], moderate in 61% [49 of 81], and severe in 28% [23 of 81]). Increase in neutrophils and reduction in eosinophils, basophils, and lymphocytes were observed (P < .05). OFC was inconclusive in 19 cases despite objective signs or neutrophilia. Regression analysis showed that a 2-day OFC protocol where only 25% of an age-appropriate portion is given on day 1 (not sex, age, culprit food, cumulative dose, and previous reaction severity) was associated with reduced odds of severe reaction compared with giving multiple doses in a single day.

CONCLUSIONS

Distinct hematological changes may help support FPIES diagnosis. Current OFC assessment criteria may not capture the broad spectrum of acute FPIES presentations. This 2-day protocol may be associated with a reduced risk of severe reactions. Future work should aim to develop safer OFC and non-OFC diagnostics for FPIES.

IgE and non-IgE food allergy: A review of immunological mechanisms

Background

Food allergic (FA) conditions have been classified as immunoglobulin E (IgE) and non-IgE-mediated reactions that affect as many as 8% of young children and 2% of adults in Western countries, and their prevalence seems to be rising. Although the immunologic basis of IgE-mediated FA is well established, the mechanisms that govern non-IgE-mediated FA are not well understood and are marked by a paucity of comprehensive insights.

Objective

The purpose of the present report is to examine the current classification and epidemiology of non-IgE-mediated FA, the latest immunologic mechanisms that underlie the three most commonly cited non-IgE FA conditions, viz., eosinophilic esophagitis, food protein-induced enterocolitis, and food protein-induced allergic proctocolitis, and explore what allergist/immunologists in practice should be aware of with regard to the condition.

Methods

An extensive research was conducted in medical literature data bases by applying terms such as FA, non-IgE allergy, tolerance, unresponsiveness, cytokines, CD4+ T helper cell pathways, and key cytokine pathways involved in FA.

Results

Current evidence now supports the view that immune dysregulation and cytokine-induced inflammation are the fundamental bases for both IgE- and non-IgE-mediated FA. The existing non-IgE-related FA literature is mostly characterized by a relative dearth of mechanistic information in contrast to IgE-mediated FA, in which the immunologic underpinnings as a T helper type 2 directed entity are well established. Although the need for future methodologic research and adherence to rigorous scientific protocols is essential, it is also necessary to acknowledge past contributions that have given much to our understanding of the condition. In the present report, a novel signature cytokine-based classification of IgE-mediated and non-IgE-mediated allergy is proposed that may offer a novel template for future research in the field of non-IgE-mediated FA.

Conclusion

The present report provides an overview of the current classification and frequency of IgE- and non-IgE-mediated FAs, and offers insights and potential solutions to address lingering questions, particularly when concerning the latest immunologic mechanisms that underlie the pathogenesis of non-IgE-mediated FA. Although some progress has been made in recent years toward making diagnostic and treatment options available for these conditions, there still remain many lingering questions and concerns to be addressed, which can be fully understood by future research.

Effect of maturation at birth on the clinical features of neonatal cow's milk protein allergy: A retrospective study

Neonatal immune regulation transitions from fetal immunity and varies with maturation status, but its role in neonatal cow's milk protein allergy (CMPA) remains unknown. We studied the association between maturation status at birth and neonatal CMPA. Clinical and laboratory data of neonates presenting with CMPA symptoms were retrospectively collected from two tertiary hospitals. Patients were assessed according to gestational age at birth: preterm, late-preterm, and full-term. Fifty-five infants (26 females, 14 preterm, 15 late-preterm, and 26 full-term) were included; 44 were negative for milk-specific immunoglobulin E. Neonatal CMPA was common during moderately premature periods. Preterm infants exhibited longer latency from initial CM exposure to disease onset, lower incidence of bloody stool, and absence of elevated monocyte counts. However, immunoreactivity to CM antigens was retained in all infants. Neonatal CMPA features varied with infant maturation status at birth. Our results improve the understanding of intestinal immunity development, fetal/neonatal immune regulation, and CMPA pathogenesis.

Effectiveness of continuous allergenic food intake for acute food protein-induced enterocolitis syndrome

Continuous intake of allergenic food is a safe and efficient treatment strategy for patients with a prolonged course of acute food protein-induced enterocolitis syndrome. The initial dose, dose escalation rate, and starting age for continuous allergenic food intake need further clarification.

Wheat-Triggered Food Protein-Induced Enterocolitis Syndrome in Celiac Children on Gluten-Free Diet: A New Clinical Association

INTRODUCTION

The association between food protein-induced enterocolitis syndrome (FPIES) and wheat ingestion in children with celiac disease is unknown at this time.

METHODS

We present seven cases of children with celiac disease who presented with symptoms of wheat-triggered acute FPIES (a-FPIES). An oral food challenge (OFC) with wheat allergen followed by 4 h of observation was performed. Activation of innate system cells was measured at baseline (T0), during symptoms (Ts), and 4 h after symptom onset (Ts + 4). A panel of human inflammatory cytokines was also performed.

RESULTS

All patients reacted to the first allergen dose. Three patients experienced a decrease of 30 mm Hg in systolic blood pressure and tachycardia and required hemodynamic resuscitation. Neutrophilia and a decrease in eosinophil count were evident at 4 h after symptom onset. At 4 h after symptom onset, cytokines (IL-6 and IL-8, and to a lesser degree, IL-10) were elevated.

CONCLUSION

In a small sample of celiac patients with wheat exposure in an OFC, symptoms and acute immunological changes in serum inflammatory cytokine profile were consistent with a-FPIES.

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.

A possible unexpected link: Could wheat elimination trigger food protein-induced enterocolitis syndrome in a celiac disease patient?

Cases of association between celiac disease and wheat allergy have been described in the literature. However, to date, no reported cases have linked celiac disease with wheat food protein-induced enterocolitis syndrome (FPIES). We report a case of this association. A child diagnosed with celiac disease at the age of 2 years, following a gluten-free diet, experienced uncontrollable vomiting, and subsequent hypotension within 2 h of accidental ingestion of wheat flour. As a result, the child required hospitalization for fluid therapy. A similar episode occurred when the child turned 5 y, again resulting from accidental gluten ingestion. This time, the symptoms included vomiting, hypotension, and a loss of consciousness, leading to hospitalization for rehydration treatment. After this second episode, on suspicion of FPIES, the patient was referred to the pediatric allergists, who confirmed the diagnosis. To our knowledge, this is the first case of an association between celiac disease and FPIES. It has been hypothesized that exclusion diets in food-allergic children may lead to an increase in specific immunoglobulin E levels for those foods and, consequently, the risk of anaphylaxis. However, FPIES is not an immunoglobulin E-mediated condition. Hence, further investigations are warranted to elucidate the underlying mechanisms linking these 2 disorders.

Mass Cytometry in Food Allergy Research

Mechanisms underlying food allergy are not well understood. Mass cytometry is a technique that allows the multiple analysis of cell surface markers and intracellular proteins by using the spectrum of rare metal isotopes of different atomic masses without channel overlap. Bioinformatic approaches are implemented to combine and reduce the information of more than 60 parameters to define immune cell subpopulations. To date, mass cytometry has revealed a great heterogeneity in human response to food antigens and that subpopulations of basophils and mononuclear cells might be mechanistically implicated in food allergy. This chapter reviews some fundamentals of mass cytometry and the contributions of this technique in elucidating the immune basis of food allergy, oral tolerance, food desensitization, phenotypes, and the cellular events occurring upon allergen-specific immunotherapy.

[Differential diagnosis in food allergy]

It is important to establish the differential diagnosis of food allergy with other disorders, for example: toxic reactions that occur in any person exposed to a sufficient amount of some allergen, and non-toxic reactions that depend on individual susceptibility (food allergy or intolerance). The differential diagnosis is decisive to establish the appropriate treatment. Food intolerance involves adverse reactions to foods without any immunological response involved, and commonly manifests with gastrointestinal symptoms (malaise, abdominal pain or diarrhea). Food allergy is an exaggerated reaction of the immune system, often mediated by IgE, that can trigger serious symptoms (hives, inflammation, respiratory distress, even anaphylaxis). The complex thing is because the symptoms sometimes overlap. To establish an accurate diagnosis, exhaustive clinical evaluation, laboratory tests and, in some cases, controlled provocation tests are required. It is important to understand these distinctions, because treatment and management vary significantly. Food intolerance involves the elimination or reduction of the food that triggers the allergic reaction and requires rigorous measures (complete avoidance of the allergen and availability of epinephrine in cases of severe reactions).

[Non-IgE-mediated food allergy]

Food allergy is an immune response to proteins in food. It usually affects 8% of children and 2% of adults in Western countries. Non-IgE-mediated food allergy mainly affects the gastrointestinal tract. Gastrointestinal food allergies are classified, by their underlying pathogenesis, as: IgE-mediated, non-IgE-mediated, or mixed. The symptoms of patients with food protein-induced allergic proctocolitis originate from local inflammation of the distal colon, which causes hematochezia in neonates. It can affect the entire gastrointestinal tract and cause symptoms of intractable emesis, with subsequent metabolic disorders and hypovolemic shock. Food protein-induced enterocolitis syndrome is a non-IgE-mediated allergy that usually appears in childhood, with prolonged repetitive vomiting, starting 1 to 4 hours after ingestion of food. The manifestation in adults is usually triggered by the consumption of shellfish. Atopic diseases affect 40-60% of patients with food protein- induced enterocolitis syndrome, including 40-50% of those with food protein-induced enteropathy and proctocolitis. Probiotics (Lactobacillus GG) can alleviate the symptoms of allergic proctocolitis induced by food proteins, by altering the composition of the intestinal microbiota. Fecal microbiota transplantation (FMT) can change intestinal microecology efficiently compared to food or probiotics.

Food protein-induced enterocolitis syndrome (FPIES): Beyond the guidelines

Background

Food protein-induced enterocolitis syndrome (FPIES) is a non-immunoglobulin E (IgE) cell mediated food allergy that can cause severe symptoms and is considered an allergic emergency.

Objective

To describe FPIES epidemiology and appraise the approach to diagnosis and management.

Methods

A review of the relevant articles published in the peer-reviewed journals since the publication of the First International FPIES Consensus Guidelines in 2017.

Results

FPIES is estimated to affect 0.51-0.9% of children and 0.22% of adults in the United States. It typically presents with protracted, projectile vomiting, which occurs within 1-4 hours of ingesting culprit foods, sometimes followed by diarrhea within 24 hours of ingestion. In ∼15-20% of severe cases, patients go into hypovolemic or distributive shock. In chronic FPIES, infants may have failure to thrive and weight loss. The most common triggers include cow's milk, oat, rice, and avocado, with egg and peanut being more frequently reported. Examples of other common fruit and vegetable triggers include banana, apple, and sweet potato. FPIES can be classified into acute, chronic, adult-onset, or atypical subtypes. FPIES is associated with comorbid atopic conditions of IgE-mediated food allergy, atopic dermatitis, asthma, allergic rhinitis, and eosinophilic esophagitis. The natural history of infantile FPIES is generally favorable, with the exception of fish FPIES. Seafood FPIES in adults has low rates of resolution over 3-5 years. Correctly identifying FPIES can be challenging because there are no specific biomarkers for diagnosis and the constellation of symptoms may mimic those of infectious enteritis or sepsis. Management relies on dietary food avoidance, periodic re-evaluations for tolerance with oral food challenges, and management of acute reactions with rehydration and antiemetic ondansetron. Although the pathophysiology of FPIES remains poorly understood, underlying mechanisms such as cytokine release, leukocyte activation, and impaired gastrointestinal mucosal barrier function may act as cornerstones for further research.

Conclusion

Prevention, laboratory diagnostic testing, and strategies to accelerate tolerance development are urgent unmet needs in FPIES.

Lymphocyte stimulation test for diagnosing hen's egg yolk-induced enterocolitis syndrome

Background

There is currently little research into factors predicting the results of an initial diagnostic oral food challenge (OFC) test for food protein-induced enterocolitis syndrome (FPIES).

Objective

The present study aimed to identify predictors of the diagnosis of hen's egg yolk-induced FPIES (HEY-FPIES).

Methods

The present monocentric study was performed at Tokyo Metropolitan Children's Medical Center and included patients who underwent hen's egg yolk OFC (HEY-OFC) between March 2018 and March 2023 to assess for HEY-FPIES. The baseline characteristics of the groups and HEY-OFC positivity or negativity were then compared. Univariate analysis was conducted by using the Mann-Whitney U test or Fisher exact test. Receiver operator characteristic analysis was used to create probability curves.

Results

In total, 35 patients were analyzed; of these, 17 were HEY-OFC-positive. No significant difference was observed between the HEY-OFC-positive and HEY-OFC-negative groups in terms of background factors except for the HEY-LST value, which was significantly higher in the HEY-LST group (P = .027). Receiver operator characteristic analysis demonstrated that the area under the curve for HEY-OFC positivity using the HEY-LST value was 0.719 (95% CI = 0.541-0.897). The statistically optimal cutoff value for the HEY-LST was 610%, which had a clinical sensitivity and specificity of 64.7% and 83.3%, respectively.

Conclusions

The present study demonstrated that the HEY-LST may be a useful predictor of the result of an initial OFC for HEY-FPIES.

Diagnostic and Management Strategies of Food Protein-Induced Enterocolitis Syndrome: Current Perspectives

Food protein-induced enterocolitis syndrome (FPIES) is a form of non-IgE mediated food allergy that presents with delayed gastrointestinal symptoms after ingestion of the trigger food. The data regarding FPIES are sparse, despite being recognized as a distinct clinical entity. This narrative review presents the characteristics of this disorder in the pediatric population, as well-standard diagnostic and management protocols. FPIES can be classified into acute and chronic subtypes, and some cases may develop into an IgE-mediated allergy. Given that skin prick tests and specific IgE levels are negative in the majority of cases, diagnosis relies on clinical history and oral food challenges. Management involves elimination diets, assessment of tolerance through oral food challenges, and rehydration in the event of a reaction. Future research should focus on improving diagnostic methods, illustrating underlying pathogenesis and biomarkers, and assessing long-term natural history. Increased knowledge and awareness for FPIES are required.

Pearls and pitfalls in food protein-induced enterocolitis syndrome (FPIES)

Background: Food protein-induced enterocolitis syndrome (FPIES) is a rare, non-immunoglobulin E (IgE) mediated gastrointestinal food hypersensitivity. It is a clinical diagnosis commonly characterized by profuse vomiting 1 to 4 hours after ingestion of the triggering food(s). Objective: The objective was to increase awareness of FPIES and review the epidemiology, clinical presentation, pathogenesis, diagnosis, and management of FPIES. The lack of availability of a definite biomarker or diagnostic tool often leads to a delay in diagnosis. Methods: A literature search of salient articles that described case reports and case series of FPIES and their management were analyzed. Results: A case of FPIES with a literature review is presented with emphasis on clinical pearls and pitfalls. FPIES is a diagnosis of exclusion and the mainstay of treatment is avoidance of the trigger food(s) for at least 12-18 months from the last exposure. Conclusion: As FPIES is a non-IgE-mediated reaction, allergy testing via skin-prick test or blood tests to measure food IgE antibodies is not routinely recommended. Many children outgrow FPIES by 3-4 years of age. Supervised oral food challenge is recommended to assess acquisition of tolerance.

A case report of acute food protein-induced enterocolitis syndrome to walnut

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a delayed, non-IgE-mediated food allergy. This syndrome was once thought to be rare, but emerging literature suggests an increasing incidence along with more foods being implicated. Also, with the introduction of guidelines on early peanut introduction, peanut-induced FPIES seems to be increasing in Australia and USA. Although most patients are diagnosed with FPIES within the first year of life, most commonly with food triggers to cow's milk or soy, other phenotypes exist in comparison to this classic presentation. In this case report, we present a patient with late onset of acute FPIES at age 3 to walnut.

CASE PRESENTATION

We describe a case of FPIES in a 12-year-old boy who had recurrent episodes of repetitive emesis, that began at age 3, each time after consuming walnuts. Mom does not give a history of intentional feeding (or avoidance) of walnut and/ or pecans. She also described possible reactions with pine nuts and macadamia. He was assessed with an oral food challenge to walnut, which triggered an episode of acute FPIES. He developed vomiting with onset 2 h post-ingestion, pallor, lethargy, and required an emergency department visit for anti-emetic medications and oral rehydration therapy. He improved on the therapy and now avoids cashew, pistachio, hazelnuts, walnuts, pecans, pine nuts, and macadamia nuts.

CONCLUSIONS

This case report adds to the limited literature that exists on culprit food allergens in FPIES. We present an acute FPIES triggered by the ingestion of walnuts. The diagnosis, common food triggers, and natural history of FPIES are described. There remains a lack of information on the natural history of FPIES, especially towards uncommon food triggers and on FPIES that present beyond infancy.

Early infancy dysbiosis in food protein-induced enterocolitis syndrome: A prospective cohort study

BACKGROUND

The microbiome associations of food protein-induced enterocolitis syndrome (FPIES) are understudied. We sought to prospectively define the clinical features of FPIES in a birth cohort, and investigate for the evidence of gut dysbiosis.

METHODS

We identified children diagnosed with FPIES in the Gastrointestinal Microbiome and Allergic Proctocolitis Study, a healthy infant cohort. Children were assessed and stools were collected at each well child visit. The clinical features of the children with FPIES were summarized. Stool microbiome was analyzed using 16S rRNA sequencing comparing children with and without FPIES.

RESULTS

Of the 874 children followed up for 3 years, 8 FPIES cases (4 male) were identified, yielding a cumulative incidence of 0.92%. The most common triggers were oat and rice (n = 3, each) followed by milk (n = 2). The children with FPIES were more likely to have family history of food allergy (50% vs. 15.9% among unaffected, p = .03). The average age of disease presentation was 6 months old. During the first 6 months of life, stool from children with FPIES contained significantly less Bifidobacterium adolescentis, but more pathobionts, including Bacteroides spp. (especially Bacteroides fragilis), Holdemania spp., Lachnobacterium spp., and Acinetobacter lwoffii. The short-chain fatty acid (SCFA)-producing Bifidobacterium shunt was expressed significantly less in the stool from FPIES children.

CONCLUSIONS

In this cohort, the cumulative incidence over the 3-year study period was 0.92%. During the first 6 months of life, children with FPIES had evidence of dysbiosis and SCFA production pathway was expressed less in their stool, which may play an important role in the pathogenesis of FPIES.

Development of an action plan for acute food protein-induced enterocolitis syndrome in Japan

Reports of food protein-induced enterocolitis syndrome (FPIES) in Japan have been increasing. However, the disease itself and the treatment options are poorly understood by both patients and medical professionals. The objective of this study is to develop an action plan for acute FPIES in Japan. We prepared a single-sheet action plan that describes the management of acute FPIES episodes for caregivers on one side and medical professionals on the reverse side. To evaluate the content of the action plan, we distributed a questionnaire to caregivers of patients with FPIES and to physicians who would encounter patients with FPIES. Changes to the FPIES action plan were made based on the feedback from the participants. The Delphi method was utilized to finalize the action plan. The participants of the initial survey found the action plan to be useful but the process for determining severity to be impractical. After discussion, the authors made appropriate improvements. By the Delphi method, consensus was reached on the revised FPIES action plan. In conclusion, this Japanese FPIES action plan was created by physicians from multiple subspecialties and caregivers of patients with FPIES. The action plan may improve the management of acute FPIES reactions in the Japanese community.

Untargeted serum metabolomic analysis reveals a role for purinergic signaling in FPIES

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy with a typical onset in infancy. Its symptoms are distinct from those of IgE-mediated food allergies and include severe repetitive vomiting, lethargy, and pallor. FPIES reactions are associated with TH17 cytokines and a systemic innate immune activation; however, the link between immune activation and symptoms is poorly understood.

OBJECTIVE

Our aim was to use an untargeted metabolomics approach to identify novel pathways associated with FPIES reactions.

METHODS

Serum samples were obtained before, during, and after oral food challenge (OFC) (10 subjects with FPIES and 10 asymptomatic subjects), and they were analyzed by untargeted metabolomics. Two-way ANOVA with false discovery rate adjustment was used for analysis of metabolites. Stomach and duodenal biopsy specimens from non-FPIES donors were stimulated with adenosine in vitro and serotonin measured by immunoassay.

RESULTS

The levels of a total of 34 metabolites, including inosine and urate of the purine signaling pathway, were increased during OFCs performed on the patients with symptomatic FPIES compared with the levels found for asymptomatic subjects. Expression of the purine receptors P2RX7 and P2RY10 and the ectonucleotidase CD73 in peripheral blood was significantly reduced after OFC of the patients with FPIES. The level of the serotonin metabolite 5-hydroxyindoleacetate was significantly elevated after reaction. Adenosine stimulation of gastric and duodenal biopsy specimens from FPIES-free donors induced a significant release of serotonin, suggesting a link between purinergic pathway activation and serotonin release.

CONCLUSIONS

Activation of the purinergic pathway during FPIES reactions provides a possible mechanism connecting inflammation and vomiting by triggering serotonin release from gastric and duodenal mucosa.

Gut Microbiome Proteomics in Food Allergies

Food allergies (FA) have dramatically increased in recent years, particularly in developed countries. It is currently well-established that food tolerance requires the strict maintenance of a specific microbial consortium in the gastrointestinal (GI) tract microbiome as alterations in the gut microbiota can lead to dysbiosis, causing inflammation and pathogenic intestinal conditions that result in the development of FA. Although there is currently not enough knowledge to fully understand how the interactions between gut microbiota, host responses and the environment cause food allergies, recent advances in '-omics' technologies (i.e., proteomics, genomics, metabolomics) and in approaches involving systems biology suggest future headways that would finally allow the scientific understanding of the relationship between gut microbiome and FA. This review summarizes the current knowledge in the field of FA and insights into the future advances that will be achieved by applying proteomic techniques to study the GI tract microbiome in the field of FA and their medical treatment. Metaproteomics, a proteomics experimental approach of great interest in the study of GI tract microbiota, aims to analyze and identify all the proteins in complex environmental microbial communities; with shotgun proteomics, which uses liquid chromatography (LC) for separation and tandem mass spectrometry (MS/MS) for analysis, as it is the most promising technique in this field.

Recent trends in food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis syndrome (FPIES) was first described in detail in the late 20th century as a non-IgE-mediated food allergy characterized by delayed gastrointestinal symptoms after ingestion of a trigger food. Although the initial case series reported infants reacting to cow's milk- and soy-based formulas, we now recognize that FPIES affects patients across the age spectrum. This brief review highlights our evolving understanding of FPIES with a discussion of triggers, epidemiology, food challenges, and pathophysiology.

Recent Update in Food Protein-Induced Enterocolitis Syndrome: Pathophysiology, Diagnosis, and Management

Food protein-induced enterocolitis syndrome (FPIES), though first reported in the 1970s, remains poorly understood and likely underdiagnosed. It is a non-immunoglobulin E (IgE)-mediated food allergy syndrome, most commonly identified in infancy and childhood. It can manifest as a constellation of symptoms following food ingestion, including repetitive and projectile emesis (1-4 hours), accompanied by pallor, lethargy, muscular hypotonia, and diarrhea (5-10 hours). In more severe reactions, significant leukocytosis with neutrophilia, thrombocytosis, metabolic derangements, methemoglobinemia, anemia, low albumin, and total protein may be present. Hypotension and ultimately hypovolemic distributive shock may occur in up to 15%-20% of cases. The diagnosis of FPIES is challenging and providers continue to face difficulties in management. This review article aims to highlight the most recent updates in epidemiology, natural history, pathophysiology, potential diagnostic markers, and guidelines for the management of FPIES.

Intestinal microbiota is modified in pediatric food protein-induced enterocolitis syndrome

Background

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food hypersensitivity that affects the gastrointestinal system, especially in children, who often present with more severe clinical manifestations than adults do. Although its pathogenesis is poorly understood and biomarkers are still lacking, scientific evidence suggests that gut microbiota may play an important role in the development of FPIES.

Objective

We aimed to compare the composition of gut microbiota in children with FPIES with that in age- and sex-matched healthy controls.

Methods

We analyzed the gut microbiota profiles in fecal samples of 17 patients with FPIES (case patients) and 12 age-matched healthy children (controls) by tag sequencing of the 16S ribosomal RNA gene hypervariable V4-V5 regions. Subjects' sociodemographic, clinical, and food diary variables were described and compared between groups by using inferential statistical tests. Nonparametric linear discriminant analysis was performed for intestinal microbiota data.

Results

Patients with confirmed cases FPIES (n = 17; average patient age, 7.5 ± 3.2 years) and controls without FPIES or any atopy (n = 12, average patient age, 6.9 ± 2.7 years) were included. Fish was the main FPIES-inducing allergen in 65% of the cases. The patients with FPIES showed higher proportions of Lachnospiraceae spp (P < .0286) and a lower proportion of Ruminococcaceae spp (P < .0066), Lactobacillaceae spp (P < .0075), and Leuconostocaceae spp (P < .0173) than the controls.

Conclusions

Our data clearly show a different gut microbial signature in patients with FPIES, suggesting a new potential avenue for aiding the diagnosis and clinical management of FPIES. Larger studies are needed to confirm these results.

Down Syndrome in FPIES: An Overwhelming and Unexpected Prevalence

Down syndrome (DS) is one of the most common chromosomal anomalies. Gastrointestinal disorders in DS are predominantly related to anatomical anomalies and celiac disease. In 2015, the first two cases of non-IgE-mediated food allergy in patients with DS were described. However, gastrointestinal symptoms experienced by subjects with DS have never been related to a possible non-IgE-mediated food allergy and a Food Protein-induced Enterocolitis syndrome (FPIES). A retrospective descriptive single-center study was conducted. Subjects included were children with acute FPIES who entered our institutional follow-up protocol between January 2013 and January 2020. Among the 85 patients (forty-nine boys—57.6%), ten (11.76%) were children with DS. In our population, the FPIES triggers included different foods (such as milk, egg, fruit, fish, wheat, soy, beef, etc.). Nine patients with DS showed FPIES reactions after ingesting cow’s milk (one even with beef and three with soy), while the last one was affected by FPIES to fish. Considering the subgroup of patients affected by cow’s milk FPIES (40 subjects overall), 22.5% had a diagnosis of DS. Patients with DS experienced acute FPIES reactions with a severity degree slightly higher than that reported in other patients, ranging from mild-moderate to severe or very severe. During the acute reactions, the patients with DS showed increased white blood cell production, absolute neutrophil count and C-reactive protein levels. This series provides a starting point for novel hypothesis-testing clinical research and possible specific immunological alterations in FPIES children with or without DS.

Adult Food Protein-Induced Enterocolitis Syndrome

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE, cell-mediated food allergy, commonly diagnosed in infants and young children. In recent years, new-onset adult FPIES has been recognized. The underlying pathogenic mechanism of FPIES has yet to be elucidated, thus disease-specific diagnostic biomarkers have yet to be determined and an oral food challenge (OFC) remains the gold-standard for the diagnosis. Pediatric patients with FPIES classically present with symptoms of delayed, repetitive vomiting approximately 1 to 4 hours following ingestion of a food allergen. However, adults with FPIES have been reported to have a different symptom profile and different food triggers compared to the pediatric FPIES population. The current FPIES diagnostic criteria may not be appropriate for the diagnosis of adult FPIES patients, thus an oral food challenge remains a diagnostic tool. This review provides an overview of the current literature on the clinical presentation, epidemiology, diagnosis, triggers and management of adult FPIES.

Food allergy in children-the current status and the way forward

Food allergy in children is a major health concern, and its prevalence is rising. It is often over-diagnosed by parents, resulting occasionally in unnecessary exclusion of some important food. It also causes stress, anxiety, and even depression in parents and affects the family's quality of life. Current diagnostic tests are useful when interpreted in the context of the clinical history, although cross-sensitivity and inability to predict the severity of the allergic reactions remain major limitations. Although the oral food challenge is the current gold standard for making the diagnosis, it is only available to a small number of patients because of its requirement in time and medical personnel. New diagnostic methods have recently emerged, such as the Component Resolved Diagnostics and the Basophil Activation Test, but their use is still limited, and the latter lacks standardisation. Currently, there is no definite treatment available to induce life-long natural tolerance and cure for food allergy. Presently available treatments only aim to decrease the occurrence of anaphylaxis by enabling the child to tolerate small amounts of the offending food, usually taken by accident. New evidence supports the early introduction of the allergenic food to infants to decrease the incidence of food allergy. If standardised and widely implemented, this may result in decreasing the prevalence of food allergy.

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.

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.

Association of Antibiotic Usage with Food Protein-Induced Enterocolitis Syndrome Development from a Caregiver's Survey

Background

Food protein-induced enterocolitis syndrome (FPIES) is a frequently misdiagnosed, serious, non-IgE mediated food allergy, and the precise mechanism of disease is unknown. Acute FPIES typically presents with repetitive, profuse vomiting approximately 1-4 hours post ingestion of a food trigger. Chronic FPIES is considered less common and less well characterized.

Objective

We aimed to better describe FPIES and identify factors that may influence FPIES development through use of a self-reported, caregiver's survey.

Methods

FPIES and allergy-free infant caregivers completed a survey regarding lifestyle factors that may influence allergy acquisition such as: antibiotic usage and delivery mode. FPIES caregivers reported symptoms, number of food triggers, type of FPIES, and symptoms from breastmilk ingestion. FPIES infants were compared to allergy-free infants to identify factors potentially associated with FPIES.

Results

Infant and prenatal maternal antibiotic usage was higher in FPIES infants compared to allergy-free infants (43.8% vs 20.6% and 48.8% vs 23.57%, respectively, p< 0.05). When compared to infants with ACUTE FPIES alone, infants described as BOTH acute and chronic FPIES reported earlier onset of symptoms, more non-specific symptoms and symptoms triggered by breast milk, more antibiotic exposure, and more food triggers (p< 0.05).

Conclusion

Antibiotic usage was significantly higher in FPIES infants when compared to allergy-free infants. Work is needed to elucidate the role of antibiotic usage in the etiology of FPIES. Infants reported to have BOTH acute and chronic FPIES were significantly different from infants with ACUTE FPIES alone highlighting the need to more closely examine these different subtypes of FPIES.

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.

Achieving Precision Medicine in Allergic Disease: Progress and Challenges

Allergic diseases (atopic dermatitis, food allergy, eosinophilic esophagitis, asthma and allergic rhinitis), perhaps more than many other traditionally grouped disorders, share several overlapping inflammatory pathways and risk factors, though we are still beginning to understand how the relevant patient and environmental factors uniquely shape each disease. Precision medicine is the concept of applying multiple levels of patient-specific data to tailor diagnoses and available treatments to the individual; ideally, a patient receives the right intervention at the right time, in order to maximize effectiveness but minimize morbidity, mortality and cost. While precision medicine in allergy is in its infancy, the recent success of biologics, development of tools focused on large data set integration and improved sampling methods are encouraging and demonstrates the utility of refining our understanding of allergic endotypes to improve therapies. Some of the biggest challenges to achieving precision medicine in allergy are characterizing allergic endotypes, understanding allergic multimorbidity relationships, contextualizing the impact of environmental exposures (the “exposome”) and ancestry/genetic risks, achieving actionable multi-omics integration, and using this information to develop adequately powered patient cohorts and refined clinical trials. In this paper, we highlight several recently developed tools and methods showing promise to realize the aspirational potential of precision medicine in allergic disease. We also outline current challenges, including exposome sampling and building the “knowledge network” with multi-omics integration.

Influences of non-IgE-mediated cow's milk protein allergy-associated gut microbial dysbiosis on regulatory T cell-mediated intestinal immune tolerance and homeostasis

Gut microbial dysbiosis is closely associated with cow's milk protein allergy (CMPA) during infancy. Recent research has highlighted the crucial role of the commensal microbiota-induced intestinal regulatory T (Treg) cell response in the development of oral tolerance and protection against IgE-mediated food allergies. However, the influences of CMPA (particularly non-IgE-mediated CMPA)-associated microbial dysbiosis on Treg cell-mediated intestinal immune tolerance and homeostasis remain poorly characterized. To investigate this issue, fecal microbiota from infant donors with food protein-induced allergic proctocolitis (FPIAP) associated with cow's milk, which is the most frequent clinical type of non-IgE-mediated gastrointestinal CMPA, and from age-matched healthy controls were transplanted into germ-free mice in this study. Two weeks post fecal microbiota transplantation, the gut microbiome of the recipient mice was analyzed by 16S rRNA gene sequencing, and the intestinal immunological alterations associated with the Treg cell compartment and intestinal immune homeostasis were detected. The specific gut microbial phylotypes that were potentially responsible for the disruption of intestinal immune homeostasis were also analyzed. We observed that the main characteristics of the gut microbiome in infant donors could be stably maintained in recipient mice. We also found that mice colonized with the gut microbiome from infants with cow's milk-induced FPIAP showed significant deficiencies in the accumulation and function of intestinal Treg cells. Furthermore, these mice showed disrupted intestinal immune homeostasis, which was characterized by an overactivated Th2 biased immune response. We further identified two potentially pathogenic genera that contribute to this disruption. Overall, our results highlight a destructive effect of non-IgE-mediated CMPA-associated microbial dysbiosis on intestinal immune tolerance and homeostasis. We believe these findings will help improve our understanding of the gut microbiota-mediated pathogenesis of non-IgE-mediated CMPA in the future.

New applications of advanced instrumental techniques for the characterization of food allergenic proteins

Current approaches based on electrophoretic, chromatographic or immunochemical principles have allowed characterizing multiple allergens, mapping their epitopes, studying their mechanisms of action, developing detection and diagnostic methods and therapeutic strategies for the food and pharmaceutical industry. However, some of the common structural features related to the allergenic potential of food proteins remain unknown, or the pathological mechanism of food allergy is not yet fully understood. In addition, it is also necessary to evaluate new allergens from novel protein sources that may pose a new risk for consumers. Technological development has allowed the expansion of advanced technologies for which their whole potential has not been entirely exploited and could provide novel contributions to still unexplored molecular traits underlying both the structure of food allergens and the mechanisms through which they sensitize or elicit adverse responses in human subjects, as well as improving analytical techniques for their detection. This review presents cutting-edge instrumental techniques recently applied when studying structural and functional aspects of proteins, mechanism of action and interaction between biomolecules. We also exemplify their role in the food allergy research and discuss their new possible applications in several areas of the food allergy field.