Pathophysiology of Non-IgE-Mediated Food Allergy

Development of IgE-mediated food allergies in children with history of food protein-induced allergic proctocolitis: a series of five cases

Food protein-induced allergic proctocolitis (FPIAP) is a non-IgE-mediated allergic condition that presents with hematochezia in otherwise healthy infants. It is most commonly induced by cow's milk protein via breast milk or formula. The prognosis for FPIAP is generally considered favorable with most infants achieving symptomatic resolution after diet modification. Most infants go on to tolerate the offending foods by 1-3 years of age. Over 8 years at our institution, five patients were identified and noted to have FPIAP to cow's milk during infancy with subsequent development of IgE-mediated allergic reaction to cow's milk and other foods. All five cases developed other atopic disorders (atopic dermatitis in four cases). IgE-mediated cow's milk allergy has persisted beyond the preschool years in at least two patients (currently 8 and 16 years old). For three of the patients, the IgE-mediated reaction to cow's milk was severe with development of anaphylaxis or angioedema. In addition, three patients experienced anaphylaxis or angioedema to allergens other than milk. While FPIAP is a non-IgE-mediated process traditionally thought not to progress past the first year of life, some infants with FPIAP develop severe, persistent IgE-mediated cow's milk allergy. To our knowledge, this is the first detailed clinical description of such patients.

Gut microbiome in the first 1000 days and risk for childhood food allergy

OBJECTIVE

To summarize recent data on the association between gut microbiome composition and food allergy (FA) in early childhood and highlight potential host-microbiome interactions that reinforce or abrogate oral tolerance.

DATA SOURCES

PubMed search of English-language articles related to FA, other atopic disease, and the gut microbiome in pregnancy and early childhood.

STUDY SELECTIONS

Human studies published after 2015 assessing the relationship between the gut bacteriome and virome in the first 2 years of life and FA or food sensitization development in early childhood were prioritized. Additional human studies conducted on the prenatal gut microbiome or other atopic diseases and preclinical studies are also discussed.

RESULTS

Children who developed FA harbored lower abundances of Bifidobacterium and Clostridia species and had a less mature microbiome during infancy. The early bacterial microbiome protects against FA through production of anti-inflammatory metabolites and induction of T regulatory cells and may also affect FA risk through a role in trained immunity. Infant enteric phage communities are related to childhood asthma development, though no data are available for FA. Maternal gut microbiome during pregnancy is associated with childhood FA risk, potentially through transplacental delivery of maternal bacterial metabolites, though human studies are lacking.

CONCLUSION

The maternal and infant microbiomes throughout the first 1000 days of life influence FA risk through a number of proposed mechanisms. Further large, longitudinal cohort studies using taxonomic, functional, and metabolomic analysis of the bacterial and viral microbiomes are needed to provide further insight on the host-microbe interactions underlying FA pathogenesis in childhood.

Engineering nanoparticle therapeutics for food allergy

Food allergy is a growing public health issue among children and adults that can lead to life-threatening anaphylaxis following allergen exposure. The criterion standard for disease management includes food avoidance and emergency epinephrine administration because current allergen-specific immunotherapy treatments are limited by adverse events and unsustained desensitization. A promising approach to remedy these shortcomings is the use of nanoparticle-based therapies that disrupt disease-driving immune mechanisms and induce more sustained tolerogenic immune pathways. The pathophysiology of food allergy includes multifaceted interactions between effector immune cells, including lymphocytes, antigen-presenting cells, mast cells, and basophils, mainly characterized by a TH2 cell response. Regulatory T cells, TH1 cell responses, and suppression of other major allergic effector cells have been found to be major drivers of beneficial outcomes in these nanoparticle therapies. Engineered nanoparticle formulations that have shown efficacy at reducing allergic responses and revealed new mechanisms of tolerance include polymeric-, lipid-, and emulsion-based nanotherapeutics. This review highlights the recent engineering design of these nanoparticles, the mechanisms induced by them, and their future potential therapeutic targets.

Dietary Intervention during Weaning and Development of Food Allergy: What Is the State of the Art?

Food allergy (FA) affects approximately 6-8% of children worldwide causing a significant impact on the quality of life of children and their families. In past years, the possible role of weaning in the development of FA has been studied. According to recent studies, this is still controversial and influenced by several factors, such as the type of food, the age at food introduction and family history. In this narrative review, we aimed to collect the most recent evidence about weaning and its role in FA development, organizing the gathered data based on both the type of study and the food. As shown in most of the studies included in this review, early food introduction did not show a potential protective role against FA development, and we conclude that further evidence is needed from future clinical trials.

Micronutrients in infants suffering from cow's milk allergy fed with dietary formulas and breast milk

INTRODUCTION

Cow's milk allergy (CMA) is the most common food allergy in infants. As this food allergy indicates a wide range of clinical syndromes due to immunological reactions to cow's milk proteins, we aimed to evaluate the status of micronutrients in infants suffering from cow's milk allergy.

METHODS

In this historical cohort study, infants with CMA were divided into two equal groups: breastfeeding and diet formula feeding. Data were gathered by a form, including the micronutrients such as iron, selenium, calcium, phosphorus, zinc, and vitamin D. Groups were compared and data were analyzed by the IBM SPSS version 21.

RESULTS

This study involved 60 six-month-old infants, and the findings revealed no significant difference between the two groups concerning magnesium, phosphorus, zinc, and vitamin D. However, infants in the formula-feeding group exhibited significantly elevated mean serum levels of iron and selenium, whereas breastfed infants displayed higher levels of calcium.

CONCLUSION

The findings of this research revealed a significant difference in calcium, selenium, and iron levels between formula-fed and breastfed infants, even though all variables were within the normal range for both groups. In light of these results, conducting further studies with a larger sample size and extended follow-up periods becomes imperative.

Safety and immunopharmacology of ASP0892 in adults or adolescents with peanut allergy: two randomized trials

BACKGROUND

New treatment options with improved safety and novel mechanisms of actions are needed for patients with peanut allergy.

OBJECTIVES

To evaluate the safety, tolerability, and immunogenicity of ASP0892, a peanut DNA vaccine, after intradermal (id) or intramuscular (im) administration in adult or adolescent patients with peanut allergy in two phase 1 studies.

METHODS

ASP0892 or placebo was administered every 2 weeks for a total of 4 doses. The doses were 1 mg or 4 mg id or 4 mg im for adults, and 1 mg or 4 mg id for adolescents. Immunologic parameters were assessed longitudinally.

RESULTS

Thirty-one adults (mean age 24.3 years, 17 males) received ASP0892 (9, 8, 8 patients for 1 mg id, 4 mg id or 4 mg im, respectively) or placebo (2 patients/group). Twenty adolescents (mean age 14.2 years, 11 males) received ASP0892 (8 patients/group) or placebo (2 patients/group). In both studies, the most common treatment-emergent adverse event (TEAE) was injection site pruritus. No deaths or treatment withdrawal were related to TEAEs. No serious TEAEs related to treatment were observed in adult or adolescent patients. ASP0892 treatment led to modest increases in allergen-specific IgG and/or IgG4 in adults (1 mg id, 4 mg im) and adolescents (1 mg id, 4 mg id). No improvements in clinical outcomes, including double-blind placebo-controlled food challenge, were found after ASP0892 treatment.

CONCLUSIONS

In two phase 1 studies, ASP0892 was well tolerated with modest but not clinically relevant changes in immune responses.

CLINICALTRIALS

GOV IDENTIFIERS

NCT02851277, NCT03755713.

Feeding Characteristics in Children With Food Allergies: A Scoping Review

BACKGROUND

Food allergy (FA) affects approximately 8% of children and may be immunoglobulin E (IgE)-mediated or non-IgE-mediated. It is recognized clinically that children with both subtypes of FA may present with features of pediatric feeding disorder (PFD); however, there is currently a limited detail of presenting characteristics.

OBJECTIVE

The objective of this study was to synthesize the current evidence regarding the feeding characteristics of children with FA, with a focus on the feeding skills and psychosocial domains of PFD.

METHOD

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. Papers published between 2001 and 2022 describing feeding characteristics in the feeding skills and psychosocial domains in children with FA/history of FA were included. Papers that focused solely on characteristics from the medical or nutritional domains were excluded. Descriptive information regarding demographics, methodology, allergy profile and history, and the characteristics of PFD observed was extracted using a preconceived data extraction form.

RESULTS

Overall, 40 papers contained descriptions of feeding characteristics of children with non-IgE-mediated FA (n = 22) and IgE-mediated FA (n = 11), while four were nonspecific. In the psychosocial domain, food refusal/aversion, anxiety with eating, and poor intake were the most frequently reported, regardless of FA subtype. Less information was reported regarding feeding skills, although slowness in eating, immature diet, and delays in oral sensory-motor skills were described.

CONCLUSIONS

Children with FA/history of FA may present with a range of characteristics that map across the feeding skill and psychosocial domains of PFD. Systematic research is needed to fully describe the feeding characteristics of children with FA.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24562732.

The dichotomy of regulatory B cells in cancer versus allergic disease

Regulatory B cells (Bregs) are an immunosuppressive cell phenotype that affects the immune system by limiting the inflammatory cascade. Dysregulation of Bregs can interestingly play a dichotomous role in the pathophysiology of many diseases and is especially highlighted when examining cancer pathology compared to allergic disease. This study reviews the existing literature on Bregs and compares their role in allergic disease in contrast to cancer development. Upregulation of Bregs in cancer states has been associated with poor prognostic outcomes across various cancer types, and Breg proliferation was associated with chronic interferon signaling, activation of the BCR-BTK (B cell receptor-Bruton's tyrosine kinase) pathway, and release of C-X-C motif ligand 13. In contrast, Breg dysfunction has been identified as a key mechanism in many allergic diseases, such as allergic asthma, allergic rhinitis, atopic dermatitis, and contact dermatitis. Development of Breg-targeted immunotherapies is currently at the preclinical level, but strategies differentially focus on Breg depletion in cancer versus Breg stimulation in allergy. Our review highlights the divergent functions that Bregs play in cancer compared to allergy. We conclude that natural homeostasis hinges on a fine balance between the dichotomous role of Bregs-over or underactivation can result in a pathological state.

Adrenaline autoinjectors for Australian out-of-hospital anaphylaxis: where to from here?

Intramuscular adrenaline autoinjectors are accepted as first-line treatment for out-of-hospital anaphylaxis but face ongoing issues of patient nonadherence related to drug expiry, availability, correct administration, and public recognition of the disease. Adrenaline is associated with possible harms in patients with defined comorbidities but is still considered preferable. Further research and policy is required to facilitate the effective treatment of anaphylaxis.

[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.

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.

Pseudo-Allergies in the Emergency Department: A Common Misdiagnosis of Hypersensitivity Type 1 Allergic Reaction

Type-1 hypersensitivity reaction represents an acute IgE-mediated reaction that can cause life-threatening conditions, such as anaphylactic shock, angioedema, and airway obstruction. Other reactions that can mimic type-1 hypersensitivity reactions include IgE-independent mast cell degranulation, bradykinin-mediated reactions, leukotrienes-mediated reactions, and pseudo-allergies. We use the term pseudo-allergy in this article for histamine-mediated reactions that are mast cell-independent. We did not discuss pseudo-allergic reactions that are not acute or life-threatening, such as celiac disease, Heiner's syndrome, eosinophilic esophagitis, and food protein-induced enterocolitis in our article because the emergency department is not the primary location to diagnose or treat these reactions. Herein, we present some allergic-like reactions that can be life-threatening, such as scombroid food poisoning (SFP), bradykinin-induced angioedema, IgE-independent angioedema, opioid-induced angioedema, and non-steroidal anti-inflammatory drug (NSAID)-induced hypersensitivity and angioedema. These reactions may have different treatments based on their mechanism of reaction. Histamine-mediated reactions, such as SFP, histamine-mediated angioedema, and mast cell degranulation induced by NSAIDs, and opioids can be treated with antihistamines, epinephrine, and corticosteroids. Bradykinin-induced angioedema, including hereditary angioedema and acquired angioedema, can be treated with fresh frozen plasma. Hereditary angioedema can be treated with many FDA-approved targeted medications, such as plasma-derived C1-INH, plasma kallikrein inhibitor (Ecallantide), and selective bradykinin-2 receptor antagonist (Icatibant). However, these targeted agents are not well-studied enough to be used for acquired angioedema. It is crucial for emergency medicine physicians to be familiar with and predict these reactions to prevent misdiagnosis, be prepared to treat these life-threatening conditions appropriately without delay and eliminate patients' exposure to any unnecessary investigations or treatments.

Evolution of Food Protein-Induced Enterocolitis Syndrome (FPIES) Index Trigger Foods and Subsequent Reactions After Initial Diagnosis

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy treated by trigger food avoidance and supportive care. Whether the prevalence of different trigger foods is changing with evolving food introduction patterns is unknown. The rate and nature of subsequent reactions after initial diagnosis have not been fully studied.

OBJECTIVE

We sought to characterize how trigger foods have changed over time and investigate the nature of subsequent reactions after initial diagnosis.

METHODS

We collected data regarding patients' FPIES reactions from 347 patients seen in the University of Michigan Allergy and Immunology clinic for FPIES from 2010 to 2022. Inclusion criteria consisted of pediatric patients diagnosed with FPIES by an allergist based on international consensus guidelines.

RESULTS

Most foods including less commonly cited FPIES triggers increased in frequency over time. The most common index trigger was oat. A total of 32.9% (114 of 347) patients experienced a subsequent reaction after education on trigger avoidance and safe home introduction of new foods, with 34.2% (41 of 120) of subsequent reactions to new triggers at home and 45% (54 of 120) to known triggers at home. Of patients reacting subsequently, 28% (32 of 114) experienced a subsequent reaction necessitating an emergency department visit. The most common new subsequent reaction triggers were egg and potato, whereas peanut most commonly triggered reactions on oral food challenge.

CONCLUSIONS

The risk profile of FPIES triggers may be evolving over time, though high-risk FPIES foods remain common. The subsequent reaction rate after counseling indicates that home food introduction poses risk. This study highlights the need for improved safety of new food introduction and/or prediction methods for FPIES to help prevent potentially dangerous home FPIES reactions.

Risk factors predisposing children to food allergies

BACKGROUND

Food allergies are the most common cause of anaphylaxis in children, and their incidence is increasing globally. The aim of this study was to determine the risk factors leading to food allergies in childhood.

METHODS

Children with food allergies and non-atopic healthy children were compared using a questionnaire that included prenatal, neonatal, and postnatal risk factors.

RESULTS

A total of 314 subjects, 155 patients and 159 healthy children for the control group, were enrolled in the study. The median age of patients with a food allergy at diagnosis was 6 months (1-156 months), and 71 patients (45.8%) were males. The median age of the control group was 12 months (1-61 months), and 67.0% were males. Older maternal age (P = 0.023), birth by caesarean section (P = 0.001), birth in the summer or autumn (P = 0.011), crowded housing (P = 0.001), damp houses (P = 0.001), being fed with breast milk and complementary food (P = 0.001), use of synthetic bedding (P = 0.024), and being the oldest child in the family (P = 0.001) were the considered risk factors for an immunoglobulin-E (IgE)-mediated food allergy. A low frequency of yoghurt consumption by mother (P = 0.001) and use of wool bedding (P = 0.018) were identified as risk factors for non-IgE-mediated food allergies. Low socioeconomic status (P = 0.001) played a protective role against both IgE- and non-IgE-mediated food allergies whereas breastfeeding played a protective role against IgE-mediated food allergies (P = 0.030).

CONCLUSION

The most important aspect of this study was that it separately identified prenatal, neonatal, and postnatal risk factors for IgE- and non-IgE-mediated food allergies.

Update on In Vitro Diagnostic Tools and Treatments for Food Allergies

Food allergy (FA) is an adverse immunological reaction to a specific food that can trigger a wide range of symptoms from mild to life-threatening. This adverse reaction is caused by different immunological mechanisms, such as IgE-mediated, non-IgE-mediated and mixed IgE-mediated reactions. Its epidemiology has had a significant increase in the last decade, more so in developed countries. It is estimated that approximately 2 to 10% of the world's population has FA and this number appears to be increasing and also affecting more children. The diagnosis can be complex and requires the combination of different tests to establish an accurate diagnosis. However, the treatment of FA is based on avoiding the intake of the specific allergenic food, thus being very difficult at times and also controlling the symptoms in case of accidental exposure. Currently, there are other immunomodulatory treatments such as specific allergen immunotherapy or more innovative treatments that can induce a tolerance response. It is important to mention that research in this field is ongoing and clinical trials are underway to assess the safety and efficacy of these different immunotherapy approaches, new treatment pathways are being used to target and promote the tolerance response. In this review, we describe the new in vitro diagnostic tools and therapeutic treatments to show the latest advances in FA management. We conclude that although significant advances have been made to improve therapies and diagnostic tools for FA, there is an urgent need to standardize both so that, in their totality, they help to improve the management of FA.

Current Practice in Pediatric Cow's Milk Protein Allergy-Immunological Features and Beyond

Cow's milk protein allergy is one of the most common pediatric food allergies. It poses a significant socioeconomic burden in industrialized countries and has a profound effect on the quality of life of affected individuals and their families. Diverse immunologic pathways can lead to the clinical symptoms of cow's milk protein allergy; some of the pathomechanisms are known in detail, but others need further elucidation. A comprehensive understanding of the development of food allergies and the features of oral tolerance could have the potential to unlock more precise diagnostic tools and novel therapeutic approaches for patients with cow's milk protein allergy.

The clinical and immunological basis of early food introduction in food allergy prevention

IgE-mediated food allergy has an estimated prevalence of 6%-10% in developed countries. Allergen avoidance has long been the main focus in the prevention of food allergy and late solid food introduction after 6-12 months of age was recommended in high-risk infants. However, the rising prevalence of food allergy despite delayed exposure to allergens and the observations that IgE-mediated sensitization to food products could even occur before the introduction of solid foods resulted in a shift towards early solid food introduction as an attempt to prevent IgE-mediated food allergy. Since then, many trials focused on the clinical outcome of early allergen introduction and overall seem to point to a protective effect on the development of IgE-mediated food allergies. For non-IgE-mediated diseases of food allergy, evidence of early food introduction seems less clear. Moreover, data on the underlying immunological processes in early food introduction is lacking. The goal of this review is to summarize the available data of immunological changes in early food introduction to prevent IgE and non-IgE mediated food allergy.

Management of Adult Patients with Gastrointestinal Symptoms from Food Hypersensitivity-Narrative Review

The incidence of food hypersensitivity has increased dramatically over the years not only among children but also in adults. Adult patients are usually less suspected of food hypersensitivity symptoms since food allergies are more typical for small children, with a tendency to outgrow the condition. The aim of this article is to increase awareness of hypersensitivity to food symptoms and their diagnosis and treatment possibilities among gastroenterologists and other health care professionals dealing with this type of patient. Symptoms of many gastrointestinal disorders, especially functional, may be driven by different types of mechanisms, and food intolerance or allergy should be considered as a potential cause. This article presents the current understanding of the epidemiology, diagnosis and treatment of immune- and non-immune-mediated food-induced diseases. Diagnosis of food hypersensitivity is based mainly on medical history, different types of sensitivity tests, e.g., hydrogen breath test, specific IgE (sIgE) serum concentration, tissue eosinophil count, skin tests and oral food challenges considered as a "gold standard" for food allergy. Elimination diet and pharmacologic treatment for allergy symptoms are first-line therapies. Eosinophilic gastrointestinal diseases are often caused by non-IgE-mediated food allergies, require endoscopic biopsy samples to confirm diagnosis and proper elimination diet often combined with steroids or proton pump inhibitor agents for treatment. Mast cell activation syndrome (MCAS) derives from pathologic reaction of mast cells with increased tryptase serum level as a marker. Symptoms may occur in the digestive, respiratory, skin, neurologic and cardiovascular system. Treatment is based on histamine type 1, type 2 (H1, H2) receptor antagonists and other mast cell stabilizing agents. Carbohydrate intolerances are the most common type of food hypersensitivity in adult patients, and an elimination diet is effective for reducing symptoms. Food additives hypersensitivity remains difficult to diagnose, but use of a diet low in chemical substances alleviates symptoms and helps to diagnose the triggering factors.

Diagnosis and Rationale for Action against Cow's Milk Allergy (DRACMA) Guidelines update - III - Cow's milk allergens and mechanisms triggering immune activation

Background

The immunopathogenesis of cow's milk protein allergy (CMPA) is based on different mechanisms related to immune recognition of protein epitopes, which are affected by industrial processing.

Purpose

The purpose of this WAO DRACMA paper is to: (i) give a comprehensive overview of milk protein allergens, (ii) to review their immunogenicity and allergenicity in the context of industrial processing, and (iii) to review the milk-related immune mechanisms triggering IgE-mediated immediate type hypersensitivity reactions, mixed reactions and non-IgE mediated hypersensitivities.

Results

The main cow’s milk allergens – α-lactalbumin, β-lactoglobulin, serum albumin, caseins, bovine serum albumins, and others – may determine allergic reactions through a range of mechanisms. All marketed milk and milk products have undergone industrial processing that involves heating, filtration, and defatting. Milk processing results in structural changes of immunomodulatory proteins, leads to a loss of lipophilic compounds in the matrix, and hence to a higher allergenicity of industrially processed milk products. Thereby, the tolerogenic capacity of raw farm milk, associated with the whey proteins α-lactalbumin and β-lactoglobulin and their lipophilic ligands, is lost.

Conclusion

The spectrum of immunopathogenic mechanisms underlying cow's milk allergy (CMA) is wide. Unprocessed, fresh cow's milk, like human breast milk, contains various tolerogenic factors that are impaired by industrial processing. Further studies focusing on the immunological consequences of milk processing are warranted to understand on a molecular basis to what extent processing procedures make single milk compounds into allergens.

Preventive Effects of a Human Hematopoietic Mesenchymal Stem Cell (hHMSC) Therapy in Ovalbumin-Induced Food Allergy

No effective therapeutic strategies have been developed against food allergies. Immunomodulation during early infant period could prevent the development of food allergies. We investigated the preventive effects of human hematopoietic mesenchymal stem cells (hHMSCs) in mice with ovalbumin (OVA)-induced food allergy. BALB/c mice with OVA-induced food allergy were divided into 3 groups, and each group was treated with hHMSCs or hHMSC culture medium (hHMSC-CM) or saline. Ear thickness, allergy score, rectal temperature, and diarrhea occurrence were checked. Total IgE, OVA-specific IgE, and mucosal mast cell protease-1 (mMCP-1) were measured by ELISA. Other allergic parameters were analyzed using histology specimens, RT-PCR, and flow cytometry. Treatment with hHMSCs or hHMSC-CM significantly suppressed the frequency of anaphylactic response and rectal temperature decline, reduced diarrhea, total IgE, OVA-specific IgE, and mMCP-1. While the treatment decreased the level of Th2 cytokines, it enhanced IL-10 and TGF-β1 mRNA. Exposure to hHMSC or hHMSC-CM did not generate regulatory T cells, but reduced mast cells. The immunomodulatory effect on the Th2 cytokines was greater in hHMSC-CM than in hHMSCs. hHMSC treatment may be a promising preventive intervention against food allergy. Further studies are needed to elucidate the key substances released from hHMSC to induce immune tolerance.

Allergy, Anaphylaxis, and Nonallergic Hypersensitivity: IgE, Mast Cells, and Beyond

IgE-mediated type I hypersensitivity reactions have many reported beneficial functions in immune defense against parasites, venoms, toxins, etc. However, they are best known for their role in allergies, currently affecting almost one third of the population worldwide. IgE-mediated allergic diseases result from a maladaptive type 2 immune response that promotes the synthesis of IgE antibodies directed at a special class of antigens called allergens. IgE antibodies bind to type I high-affinity IgE receptors (FcεRI) on mast cells and basophils, sensitizing them to get triggered in a subsequent encounter with the cognate allergen. This promotes the release of a large variety of inflammatory mediators including histamine responsible for the symptoms of immediate hypersensitivity. The development of type 2-driven allergies is dependent on a complex interplay of genetic and environmental factors at barrier surfaces including the host microbiome that builds up during early life. While IgE-mediated immediate hypersensitivity reactions are undoubtedly at the origin of the majority of allergies, it has become clear that similar responses and symptoms can be triggered by other types of adaptive immune responses mediated via IgG or complement involving other immune cells and mediators. Likewise, various nonadaptive innate triggers via receptors expressed on mast cells have been found to either directly launch a hypersensitivity reaction and/or to amplify existing IgE-mediated responses. This review summarizes recent findings on both IgE-dependent and IgE-independent mechanisms in the development of allergic hypersensitivities and provides an update on the diagnosis of allergy.

Immunologic and pathologic characterization of a novel swine biomedical research model for eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergy-mediated condition with an increasing incidence in both children and adults. Despite EoE's strong impact on human health and welfare, there is a large unmet need for treatments with only one recently FDA-approved medication for EoE. The goal of this study was to establish swine as a relevant large animal model for translational biomedical research in EoE with the potential to facilitate development of therapeutics. We recently showed that after intraperitoneal sensitization and oral challenge with the food allergen hen egg white protein (HEWP), swine develop esophageal eosinophilia-a hallmark of human EoE. Herein, we used a similar sensitization and challenge treatment and evaluated immunological and pathological markers associated with human EoE. Our data demonstrate that the incorporated sensitization and challenge treatment induces (i) a systemic T-helper 2 and IgE response, (ii) a local expression of eotaxin-1 and other allergy-related immune markers, (iii) esophageal eosinophilia (>15 eosinophils/0.24 mm²), and (iv) esophageal endoscopic findings including linear furrows and white exudates. Thereby, we demonstrate that our sensitization and oral challenge protocol not only induces the underlying immune markers but also the micro- and macro-pathological hallmarks of human EoE. This swine model for EoE represents a novel relevant large animal model that can drive translational biomedical research to develop urgently needed treatment strategies for EoE.