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.

Food Protein-Induced Enterocolitis Syndrome: a Comprehensive Review.

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that has been well-characterized clinically, yet it is still poorly understood. Acute FPIES is characterized by vomiting 1-4 h and/or diarrhea within 24 h after ingestion of a culprit food. Chronic FPIES is the result of chronic exposure to an offending food that can result in chronic watery diarrhea, intermittent vomiting, and failure to thrive. FPIES typically presents in infancy and self-resolves by school age in most patients. Adult-onset FPIES is rare, but it has been reported. Cow's milk and soy are the most common triggering foods in infants in the US, and as solids are introduced in the diet, FPIES reactions to grains (rice, oat) increase in prevalence. Variability in common trigger foods exists depending on the geographical origin-for example, fish is a frequent trigger in Spanish and Italian patients. Heavy reliance on a detailed history is required for the diagnosis as physical exam findings, laboratory tests, and/or imaging studies are suggestive and not specific for FPIES. Oral food challenges remain the gold standard for confirming diagnosis, and the challenge protocol may be for an individual depending on risk of reaction, prior reaction severity, and positive-specific IgE status. The recent development of diagnostic criteria in 2017 will serve to increase recognition of the disorder and allow for early implementation of management strategies. Acute management during reactions includes IV hydration, anti-emetics, and IV corticosteroids. Reaction prevention strategies include strict food avoidance until the physician deems a food reintroduction challenge clinically appropriate. Future efforts in FPIES research should be aimed at elucidating the underlying disease mechanisms and possible treatment targets.

The importance of early peanut ingestion in the prevention of peanut allergy.

INTRODUCTION: Peanut allergy appears to have increased in prevalence, is often severe and is typically life-long. Therefore, reducing its incidence through a primary prevention strategy is a priority. Guidelines on peanut introduction have evolved with time and given evidence of peanut allergy risk reduction with early infant ingestion exposure, the current US advice promotes early introduction for infants, particularly targeting those at highest risk. Areas covered: This article describes the evolution of peanut introduction guidelines in infants in the US, as shaped by key research over the last 20-30 years and culminates in the landmark LEAP study. It also compares and contrasts current iterations of peanut introduction guidelines in infants globally. Finally, the early successes and barriers of implementation of early peanut introduction guidelines are discussed. We included literature from original articles, reviews, and consensus guidelines found in database searches through December 2018. Expert commentary: LEAP guideline implementation has proven to be successful, in the study setting, in decreasing the incidence of peanut allergy. However, its implementation in the community has been met with obstacles including low awareness among stakeholders, and access to testing when needed.