Degree of hydrolysis is a poor predictor of the sensitizing capacity of whey- and casein-based hydrolysates in a Brown Norway rat model of cow's milk allergy.

The use of infant formulas (IFs) based on hydrolyzed cow's milk proteins to prevent cow's milk allergy (CMA) is highly debated. The risk of sensitization to milk proteins induced by IFs may be affected by the degree of hydrolysis (DH) as well as other physicochemical properties of the cow's milk-based protein hydrolysates within the IFs. The immunogenicity (specific IgG1 induction) and sensitizing capacity (specific IgE induction) of 30 whey- or casein-based hydrolysates with different physicochemical characteristics were compared using an intraperitoneal model of CMA in Brown Norway rats. In general, the whey-based hydrolysates demonstrated higher immunogenicity than casein-based hydrolysates, inducing higher levels of hydrolysate-specific and intact-specific IgG1. The immunogenicity of the hydrolysates was influenced by DH, peptide size distribution profile, peptide aggregation, nano-sized particle formation, and surface hydrophobicity. Yet, only the surface hydrophobicity was found to affect the sensitizing capacity of hydrolysates, as high hydrophobicity was associated with higher levels of specific IgE. The whey- and casein-based hydrolysates exhibited distinct immunological properties with highly diverse molecular composition and physicochemical properties which are not accounted for by measuring DH, which was a poor predictor of sensitizing capacity. Thus, future studies should consider and account for physicochemical characteristics when assessing the sensitizing capacity of cow's milk-based protein hydrolysates.

Assessing Pediatric Cephalosporin Allergic Reactions Through Direct Graded Oral Challenges.

BACKGROUND: Cephalosporins, ß-lactam antibiotics, commonly cause allergic reactions. OBJECTIVE: To assess the clinical characteristics and management of pediatric patients with suspected cephalosporin allergy using direct graded oral challenges (GOCs). METHODS: Children referred for suspected cephalosporin allergy at 4 Canadian clinics were recruited over 10 years. Data on demographics, clinical reaction characteristics, and management were collected through a questionnaire. Patients underwent a direct GOC (initially 10% of the treatment dose, then 90% after 20 min), and reactions were monitored 1 week postchallenge. Families were contacted annually for up to 5 years to detect subsequent antibiotic reactions. Logistic regression analysis identified factors associated with positive GOC reactions. RESULTS: Among the 136 patients reporting cephalosporin allergy, 75 (55.1%) were males with a median age of 3.9 years (interquartile range 2.3-8.7). Cefprozil represented the most common cephalosporin linked to the index reaction (67.6% of cases). Of the 136 direct GOCs, 5.1% had an immediate and 4.4% a nonimmediate reaction, respectively. Positive GOCs conducted in children with a history of skin-limited nonsevere rashes were classified as mild, benign skin rashes. Positive GOCs were more likely in children with food allergies (adjusted odds ratio 1.14; 95% confidence interval [95% CI] 1.00-1.29). CONCLUSIONS: Direct GOCs are safe and effective for diagnosing pediatric cases that report nonvesicular skin-limited symptoms while being treated with cephalosporins.

EAACI guidelines on the diagnosis of IgE-mediated food allergy.

This European Academy of Allergy and Clinical Immunology guideline provides recommendations for diagnosing IgE-mediated food allergy and was developed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Food allergy diagnosis starts with an allergy-focused clinical history followed by tests to determine IgE sensitization, such as serum allergen-specific IgE (sIgE) and skin prick test (SPT), and the basophil activation test (BAT), if available. Evidence for IgE sensitization should be sought for any suspected foods. The diagnosis of allergy to some foods, such as peanut and cashew nut, is well supported by SPT and serum sIgE, whereas there are less data and the performance of these tests is poorer for other foods, such as wheat and soya. The measurement of sIgE to allergen components such as Ara h 2 from peanut, Cor a 14 from hazelnut and Ana o 3 from cashew can be useful to further support the diagnosis, especially in pollen-sensitized individuals. BAT to peanut and sesame can be used additionally. The reference standard for food allergy diagnosis is the oral food challenge (OFC). OFC should be performed in equivocal cases. For practical reasons, open challenges are suitable in most cases. Reassessment of food allergic children with allergy tests and/or OFCs periodically over time will enable reintroduction of food into the diet in the case of spontaneous acquisition of oral tolerance.

Phase 3 Trial of Epicutaneous Immunotherapy in Toddlers with Peanut Allergy.

BACKGROUND: No approved treatment for peanut allergy exists for children younger than 4 years of age, and the efficacy and safety of epicutaneous immunotherapy with a peanut patch in toddlers with peanut allergy are unknown. METHODS: We conducted this phase 3, multicenter, double-blind, randomized, placebo-controlled trial involving children 1 to 3 years of age with peanut allergy confirmed by a double-blind, placebo-controlled food challenge. Patients who had an eliciting dose (the dose necessary to elicit an allergic reaction) of 300 mg or less of peanut protein were assigned in a 2:1 ratio to receive epicutaneous immunotherapy delivered by means of a peanut patch (intervention group) or to receive placebo administered daily for 12 months. The primary end point was a treatment response as measured by the eliciting dose of peanut protein at 12 months. Safety was assessed according to the occurrence of adverse events during the use of the peanut patch or placebo. RESULTS: Of the 362 patients who underwent randomization, 84.8% completed the trial. The primary efficacy end point result was observed in 67.0% of children in the intervention group as compared with 33.5% of those in the placebo group (risk difference, 33.4 percentage points; 95% confidence interval, 22.4 to 44.5; P<0.001). Adverse events that occurred during the use of the intervention or placebo, irrespective of relatedness, were observed in 100% of the patients in the intervention group and 99.2% in the placebo group. Serious adverse events occurred in 8.6% of the patients in the intervention group and 2.5% of those in the placebo group; anaphylaxis occurred in 7.8% and 3.4%, respectively. Serious treatment-related adverse events occurred in 0.4% of patients in the intervention group and none in the placebo group. Treatment-related anaphylaxis occurred in 1.6% in the intervention group and none in the placebo group. CONCLUSIONS: In this trial involving children 1 to 3 years of age with peanut allergy, epicutaneous immunotherapy for 12 months was superior to placebo in desensitizing children to peanuts and increasing the peanut dose that triggered allergic symptoms. (Funded by DBV Technologies; EPITOPE ClinicalTrials.gov number, NCT03211247.).

An update on recent developments and highlights in food allergy.

While both the incidence and general awareness of food allergies is increasing, the variety and clinical availability of therapeutics remain limited. Therefore, investigations into the potential factors contributing to the development of food allergy (FA) and the mechanisms of natural tolerance or induced desensitization are required. In addition, a detailed understanding of the pathophysiology of food allergies is needed to generate compelling, enduring, and safe treatment options. New findings regarding the contribution of barrier function, the effect of emollient interventions, mechanisms of allergen recognition, and the contributions of specific immune cell subsets through rodent models and human clinical studies provide novel insights. With the first approved treatment for peanut allergy, the clinical management of FA is evolving toward less intensive, alternative approaches involving fixed doses, lower maintenance dose targets, coadministration of biologicals, adjuvants, and tolerance-inducing formulations. The ultimate goal is to improve immunotherapy and develop precision-based medicine via risk phenotyping allowing optimal treatment for each food-allergic patient.

Does the Use of the "Proseek® Multiplex Inflammation I Panel" Demonstrate a Difference in Local and Systemic Immune Responses in Endometriosis Patients with or without Deep-Infiltrating Lesions?

Endometriotic lesions are able to infiltrate surrounding tissue. This is made possible partly by an altered local and systemic immune response that helps achieve neoangiogenesis, cell proliferation and immune escape. Deep-infiltrating endometriosis (DIE) differs from other subtypes through the invasion of its lesions over 5 mm into affected tissue. Despite the invasive nature of these lesions and the wider range of symptoms they can trigger, DIE is described as a stable disease. This elicits the need for a better understanding of the underlying pathogenesis. We used the "Proseek® Multiplex Inflammation I Panel" in order to simultaneously detect 92 inflammatory proteins in plasma and peritoneal fluid (PF) of controls and patients with endometriosis, as well as in particular patients with DIE, in order to gain a better insight into the systemically and locally involved immune response. Extracellular newly identified receptor for advanced gycation end-products binding protein (EN-RAGE), C-C motif Chemokine ligand 23 (CCL23), Eukaryotic translation initiation factor 4-binding protein 1 (4E-BP1) and human glial cell-line derived neurotrophic factor (hGDNF) were significantly increased in plasma of endometriosis patients compared to controls, whereas Hepatocyte Growth factor (HGF) and TNF-related apoptosis inducing ligand (TRAIL) were decreased. In PF of endometriosis patients, we found Interleukin 18 (IL-18) to be decreased, yet Interleukin 8 (IL-8) and Interleukin 6 (IL-6) to be increased. TNF-related activation-induced cytokine (TRANCE) and C-C motif Chemokine ligand 11 (CCL11) were significantly decreased in plasma, whereas C-C motif Chemokine ligand 23 (CCL23), Stem Cell Factor (SCF) and C-X-C motif chemokine 5 (CXCL5) were significantly increased in PF of patients with DIE compared to endometriosis patients without DIE. Although DIE lesions are characterized by increased angiogenetic and pro-inflammatory properties, our current study seems to support the theory that the systemic immune system does not play a major role in the pathogenesis of these lesions.

Pathogenesis, immunology, and immune-targeted management of the multisystem inflammatory syndrome in children (MIS-C) or pediatric inflammatory multisystem syndrome (PIMS): EAACI Position Paper.

Multisystem inflammatory syndrome in children (MIS-C) is a rare, but severe complication of coronavirus disease 2019 (COVID-19). It develops approximately 4 weeks after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and involves hyperinflammation with multisystem injury, commonly progressing to shock. The exact pathomechanism of MIS-C is not known, but immunological dysregulation leading to cytokine storm plays a central role. In response to the emergence of MIS-C, the European Academy of Allergy and Clinical Immunology (EAACI) established a task force (TF) within the Immunology Section in May 2021. With the use of an online Delphi process, TF formulated clinical statements regarding immunological background of MIS-C, diagnosis, treatment, follow-up, and the role of COVID-19 vaccinations. MIS-C case definition is broad, and diagnosis is made based on clinical presentation. The immunological mechanism leading to MIS-C is unclear and depends on activating multiple pathways leading to hyperinflammation. Current management of MIS-C relies on supportive care in combination with immunosuppressive and/or immunomodulatory agents. The most frequently used agents are systemic steroids and intravenous immunoglobulin. Despite good overall short-term outcome, MIS-C patients should be followed-up at regular intervals after discharge, focusing on cardiac disease, organ damage, and inflammatory activity. COVID-19 vaccination is a safe and effective measure to prevent MIS-C. In anticipation of further research, we propose a convenient and clinically practical algorithm for managing MIS-C developed by the Immunology Section of the EAACI.

Precision cut intestinal slices, a novel model of acute food allergic reactions.

BACKGROUND: Food allergy affects up to 10% of the pediatric population. Despite ongoing efforts, treatment options remain limited. Novel models of food allergy are needed to study response patterns downstream of IgE-crosslinking and evaluate drugs modifying acute events. Here, we report a novel human ex vivo model that displays acute, allergen-specific, IgE-mediated smooth muscle contractions using precision cut intestinal slices (PCIS). METHODS: PCIS were generated using gut tissue samples from children who underwent clinically indicated surgery. Viability and metabolic activity were assessed from 0 to 24 h. Distribution of relevant cell subsets was confirmed using single nucleus RNA sequencing. PCIS were passively sensitized using plasma from peanut allergic donors or peanut-sensitized non-allergic donors, and exposed to various stimuli including serotonin, histamine, FcɛRI-crosslinker, and food allergens. Smooth muscle contractions and mediator release functioned as readouts. A novel program designed to measure contractions was developed to quantify responses. The ability to demonstrate the impact of antihistamines and immunomodulation from peanut oral immunotherapy (OIT) was assessed. RESULTS: PCIS viability was maintained for 24 h. Cellular distribution confirmed the presence of key cell subsets including mast cells. The video analysis tool reliably quantified responses to different stimulatory conditions. Smooth muscle contractions were allergen-specific and reflected the clinical phenotype of the plasma donor. Tryptase measurement confirmed IgE-dependent mast cell-derived mediator release. Antihistamines suppressed histamine-induced contraction and plasma from successful peanut OIT suppressed peanut-specific PCIS contraction. CONCLUSION: PCIS represent a novel human tissue-based model to study acute, IgE-mediated food allergy and pharmaceutical impacts on allergic responses in the gut.

Food protein-induced enterocolitis syndrome in a tertiary pediatric center: safety of guideline-conforming food challenges.

Food protein-induced enterocolitis syndrome is a non-IgE-mediated reaction to food that is poorly understood, and underdiagnosed. Trigger foods can belong to any food group, but are most commonly milk, soy, rice, oat, egg, and fish. In this retrospective study (2015-2020), we describe the clinical presentations and triggers of 37 children referred to tertiary hospital with a confirmed or suspected diagnosis of food protein-inducted enterocolitis. We reviewed the safety of current recommendations by looking at the outcome of 24 oral food challenges. All of these patients presented with clear cut systemic reactions including lethargy. We also assessed the severity of the reactions. Oral food challenges occurred in the hospital day unit with the majority of patients having IV access in place. Despite a clear history of FPIES with lethargy and the requirement for re-hydration of the challenged population, 21/24 (88%) of the FPIES OFCs were successful. Of the three patients who reacted, symptoms were of moderate nature, mainly vomiting. This highlights the importance of early diagnosis and a pro-active approach to performing guideline-directed oral food challenges in patients with food protein-induced enterocolitis syndrome.

Platelet-activating factor acetylhydrolase is a biomarker of severe anaphylaxis in children.

BACKGROUND: There is limited ability to predict the severity of allergic reactions in children. Data derived predominantly from adults have implicated the platelet-activating factor pathway as a potential contributor to severe anaphylaxis. In this study, we sought to prospectively assess involvement of key components of the platelet-activating factor pathway in pediatric patients with anaphylaxis. METHODS: Forty-six pediatric patients (<18 years) presenting with acute anaphylaxis were assessed. Anaphylaxis severity was graded and serum anaphylaxis markers were measured acutely and in 36 children who returned for follow-up >4 weeks after their acute presentation. These markers were compared with pediatric laboratory reference sera. RESULTS: Severe anaphylaxis was experienced by 12/46 (26%) and mild-moderate anaphylaxis in 34/46 (74%) children. Platelet-activating factor acetylhydrolase (PAF-AH) activity was inversely associated with severe anaphylaxis: 9/12 children with severe anaphylaxis had reduced PAF-AH activity as compared with 14/34 with mild-moderate anaphylaxis (p < .05). Furthermore, 3/3 children who required intensive care had markedly reduced mean PAF-AH (nmol/ml/min) (13.73, 95%CI: 7.42-20.03) versus 20/23 who required ward/emergency department care (17.81, 95%CI: 16.80-18.83; p < .05). In children with anaphylaxis, PAF-AH during acute anaphylaxis was unchanged relative to the child's basal levels (mean, 17.26, 95%CI: 16.10-18.42 vs 17.50, 95%CI: 16.21-18.78, p = .63) and was lower than healthy pediatric controls (mean 19.21; 95%CI:18.21-20.21; p < .05). CONCLUSION: Decreased serum PAF-AH activity is a biomarker of severe anaphylaxis. Levels of this enzyme do not change from basal levels during acute anaphylaxis. Our results show that PAF-AH is a biomarker of anaphylaxis severity in children. This key regulatory enzyme may modulate susceptibility to severe anaphylaxis.