Safety and effectiveness of peanut oral immunotherapy in children under 12 months
The relevance of oral food challenge in a patient allergic to peanut and tree nuts
Peanut allergy is one of the most common food allergies in childhood. In vitro cross-sensitization between peanut and tree nuts (TN) is high, but only a subgroup of patients allergic to peanut will have a concomitant allergy to one or several TN. In this article, the authors report a case of a 12-year-old boy who experienced 1 episode of lips and mouth itching, generalized urticarial, and eyelid angioedema 20 minutes after ingestion of peanut at 4 years of age. The immunoallergological study revealed the presence of a concomitant allergy to peanut, pistachio, and cashew confirmed with medically supervised oral food challenges (OFC) in a child who had never eaten these TN. The mechanism of IgE-mediated hypersensitivity was demonstrated by positive skin prick tests (SPT) with commercial extracts, although the specific IgE (sIgE) for these foods was negative. As described in the literature, we concluded that serum peanut and TN sIgE measurements have lower sensitivity than SPT to assess IgE sensitization, and OFC is the gold standard for accurate diagnosis of food allergy. We highlight the relevance of excluding or confirming TN allergy in a peanut-allergic patient who had never ingested certain TN, and of knowing the clinical relevant cross-reactivity patterns between TN, pistachio/cashew, and walnut/pecan, that could reduce the need for OFC in clinical practice, reducing allergy rates and financial and health burdens of food allergy.
https://doi.org/10.5415/apallergy.0000000000000109
Reactivity to allergenic food contaminants: A study on products on the market
Background: The frequency and severity of reactions in food-allergic consumers exposed to unintentional food allergen contamination during production is unknown. To warn allergic consumers, it has been suggested for pre-packaged foods to be precautionary labelled when the food allergen contamination may exceed the amount to which 1%-5% of the population could react (ED01-ED05). ED01 for hazelnut and milk have been estimated at 0.1 and 0.2 mg, respectively, by the Voluntary Incidental Trace Allergen Labelling (VITAL) initiative. The respective reference doses recommended by the FAO/WHO Codex consultation are 3 and 2 mg. We evaluated the reactivity to potential traces of milk and hazelnut allergens in allergen-free pre-packaged products by children affected by severe allergies to milk and hazelnuts. Methods: Oral Food Challenges with commercially available hazelnut-free wafer biscuits and milk-free chocolate pralines were administered to patients with severe food allergies to hazelnut and cow's milk, respectively. Contamination levels of milk or hazelnut allergens were measured using chromatographic separation interfaced with triple quadrupole mass spectrometry. Results: No hazelnut allergic patient showed allergic reactions to exposure to biscuits, nor any milk allergic patient displayed allergic reactions to the dark chocolate praline. While no hazelnut trace was detected in biscuits, the praline was found to be contaminated by milk at concentrations ranging between 8 and 35 mg total protein/kg food. In our dose model, these amounts exceeded 1.5-10 times the VITAL ED01 and reached the threshold suggested by the FAO/WHO Codex consultation. Conclusions: Upon the consumption of food products available on the market, many patients with severe food allergies tolerate significantly higher doses of allergen than reference doses indicated in the VITAL system used for precautionary allergen labelling. These doses support the safety of the FAO/WHO recommended reference doses.
https://doi.org/10.1002/clt2.12301
Citrin: a novel food allergen in citrus seeds and citrus-derived pectin that shows cross-reactivity with cashew and pistachio
Background: Patients exquisitely sensitive to cashew/pistachio are at risk for allergic reactions to citrus seeds and pectin. Objective: In this study, we sought to examine whether pectin is contaminated with citrus seeds, to identify a culprit antigen in citrus seeds, and to assess for cross-reactivity among allergens in citrus seeds, citrus pectin, and cashew/pistachio. Methods: Proteins from orange seed coats, orange seed endosperms, lemon seeds, grapefruit seeds, citrus pectin, apple pectin, and grapefruit pectin were extracted. Protein concentrations in all extracts were determined and visualized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. IgE binding capacity was determined with Western blot analyses and Tandem Mass spectrometry (MS/MS) for the identification of the culprit allergen in citrus seeds and pectin. Results: In subjects with citrus seed, pectin, and cashew allergies, there was strong IgE-reactivity to bands between 17-28 kDa and 28-38 kDa. The MS/MS analysis of these bands indicated the presence of citrin as the culprit allergen. Citrin and Ana o 2 are both 11S globulins belonging to the cupin superfamily, and significant homology was demonstrated between these proteins. Conclusion: Citrus pectin may be contaminated with citrus seeds. Citrin, a newly identified allergen in citrus seeds, appears to be the culprit antigen in citrus seeds and contaminated citrus pectin. Citrin is highly homologous with Ana o 2 in cashew and Pis v 2 in pistachio, suggesting potential for cross-reactivity and providing an explanation for co-allergenicity of cashew/pistachio, citrus seeds, and citrus pectin.
https://doi.org/10.1016/j.anai.2023.08.603
Effects of hazelnut protein isolate-induced food allergy on the gut microenvironment in a BALB/c mouse model
Hazelnuts are reported as among the nuts that cause severe allergic reactions. However, few systematic studies exist on the changes in the gut microenvironment following hazelnut allergy. This study focused on the effects of hazelnut allergy on the duodenum, jejunum, ileum and colon microenvironment in vivo. We established a hazelnut protein isolate (HPI)-allergic mouse model, which was distinguished by the visible allergy symptoms, dropped temperatures and enhanced allergic inflammatory factor levels in serum, such as HPI-specific immunoglobulin E (sIgE), sIgG2a, interleukin-4, histamine, mouse mast cell protease-1, TNF-α, monocyte chemotactic protein-1 and lipopolysaccharide. For HPI sensitized mice, aggravated mast cell degranulation, severe morphologic damage and inflammatory cell infiltration were observed in the duodenum, jejunum, ileum, and colon, while goblet cell numbers were reduced in the duodenum, jejunum and ileum. Secretory IgA of the jejunum and tight junctions of the duodenum and jejunum were decreased significantly after HPI sensitization. There was no remarkable difference in the pH values of small intestinal contents, but the pH values of colonic contents were elevated, which was due to the decreased short-chain fatty acids (mainly acetate, propionate and butyrate) in the colon. The antioxidant capacity of both large and small intestinal contents declined after HPI sensitization, as evidenced by the increased malondialdehyde and decreased superoxide dismutase activity. HPI sensitization induced gut microbiota dysbiosis with decreased α diversity and altered β diversity in colonic contents. Spearman correlation analysis indicated that the increased characteristic genera, namely Bacteroides, Lactobacillus, Alloprevotella, Erysipelatoclostridium, Parabacteroides, and Helicobacter, played potentially synergistic roles in promoting allergy and gut microenvironment dysregulation.
https://doi.org/10.1039/d3fo02324a
Longitudinal dynamics of the gut microbiome and metabolome in peanut allergy development
Background: Rising rates of peanut allergy motivate investigations of its development to inform prevention and therapy. Microbiota and the metabolites they produce shape food allergy risk. Objective: To gain insight into gut microbiome and metabolome dynamics in the development of peanut allergy. Methods: We performed a longitudinal, integrative study of the gut microbiome and metabolome of infants with allergy risk factors but no peanut allergy from a multi-center cohort who were followed through mid-childhood. We performed 16S rRNA sequencing, short chain fatty acid measurements, and global metabolome profiling of fecal samples at infancy and at mid-childhood. Results: In this longitudinal, multi-center sample (n=122), 28.7% of infants developed peanut allergy by mid-childhood (mean age 9 years). Lower infant gut microbiome diversity was associated with peanut allergy development (P=0.014). Temporal changes in the relative abundance of specific microbiota and gut metabolite levels significantly differed in children who developed peanut allergy. Peanut allergy-bound children had different abundance trajectories of Clostridium sensu stricto 1 sp. (false discovery rate (FDR)=0.015) and Bifidobacterium sp. (FDR=0.033), with butyrate (FDR=0.045) and isovalerate (FDR=0.036) decreasing over time. Metabolites associated with peanut allergy development clustered within the histidine metabolism pathway. Positive correlations between microbiota, butyrate, and isovalerate and negative correlations with histamine marked the peanut allergy-free network. Conclusion: The temporal dynamics of the gut microbiome and metabolome in early childhood are distinct for children who develop peanut allergy. These findings inform our thinking on the mechanisms underlying and strategies for potentially preventing peanut allergy.
https://doi.org/10.1016/j.jaci.2023.08.012
Clinically and industrially relevant incurred reference materials to improve analysis of food allergens, milk, egg, almond, hazelnut and walnut
Measurement of food allergen protein concentrations against thresholds can improve allergen risk management and precautionary allergen labelling. Such measurement suffers well known problems which could be ameliorated by well characterised reference materials (RMs) providing meaningful information for risk assessors. We investigated the preparation and characterisation of the first consensus informed industrially and clinically relevant multi-allergen matrix RM kit for five priority allergens. It is a medium analytical difficulty processed food chocolate paste matrix (a) devoid of allergens, and (b) incurred with five allergens at the clinically relevant concentration of 10 mg kg-1 expressed as protein. The allergen raw materials: hens' egg white powder, skimmed cows' milk powder, almond powder (full fat), hazelnut powder (partially defatted), and walnut powder (partially defatted), are also available as RMs. The preparation, gravimetric traceability to the SI, homogeneity, and stability were found to be fit-for-purpose and the RMs are now available to the analytical community. https://doi.org/10.1016/j.foodchem.2023.137391
Peanut allergy: risk factors, immune mechanisms, and best practices for oral immunotherapy success
Introduction: Peanut oral immunotherapy (pOIT) is the only FDA-approved treatment for food allergy and its adoption amongst allergist immunologists and their patients is growing. pOIT is the subject of numerous clinical trials, however, the focus is often on treatment efficacy, safety, and tolerability, rather than identifying patients most likely to benefit from pOIT. Here, we review existing data on the clinical and immunological outcomes of pOIT that inform best practices for pOIT candidate selection. Areas covered: In this review, we describe the natural history of peanut allergy, summarize immunological and clinical outcomes of pOIT at different ages, discuss the optimization of pOIT in key age groups, and finally suggest an ideal age range at which to initiate pOIT for best outcomes. Expert opinion: pOIT is currently underutilized by patients and allergist-immunologists. Developing guidelines for selecting appropriate patients and optimizing treatment may help to increase access to pOIT. Many aspects of pOIT need additional study to further our understanding of the optimal timing to start pOIT, with careful consideration to clinical, immunological, and quality of life outcomes. https://doi.org/10.1080/1744666X.2023.2209318
Food-Induced Anaphylaxis: Data From the European Anaphylaxis Registry
Background: Food is one of the most common elicitors of anaphylaxis, with an increasing incidence over recent years. Objectives: To characterize elicitor-specific phenotypes and identify factors enhancing the risk or severity of food-induced anaphylaxis (FIA). Methods: We analyzed data from the European Anaphylaxis Registry applying an age- and sex-matched analysis of associations (Cramer's V) for single food triggers and calculated odds ratios (ORs) for severe FIA. Results: We identified 3,427 cases of confirmed FIA showing an age-dependent elicitor ranking (for children: peanut, cow's milk, cashew, and hen's egg; and for adults: wheat flour, shellfish, hazelnut, and soy). The age- and sex-matched analysis revealed defined symptom patterns for wheat and cashew. Wheat-induced anaphylaxis was more frequently associated with cardiovascular symptoms (75.7%; Cramer's V = 0.28) and cashew-induced anaphylaxis with gastrointestinal symptoms (73.9%; Cramer's V = 0.20). Furthermore, concomitant atopic dermatitis was slightly associated with anaphylaxis to hen's egg (Cramer's V = 0.19) and exercise was strongly associated with anaphylaxis to wheat (Cramer's V = 0.56). Additional factors influencing the severity were alcohol intake in wheat anaphylaxis (OR = 3.23; CI, 1.31-8.83) and exercise in peanut anaphylaxis (OR = 1.78; CI, 1.09-2.95). Conclusions: Our data show that FIA is age-dependent. In adults, the range of elicitors inducing FIA is broader. For some elicitors, the severity of FIA seems to be related to the elicitor. These data require confirmation in future studies considering a clear differentiation between augmentation and risk factors in FIA. https://doi.org/10.1016/j.jaip.2023.03.026
Interaction of mediators and effector cells in cashew nut-induced anaphylaxis
Background: The underlying mechanisms of an immediate food-induced allergic reaction involve mast-cell degranulation and recruitment of other effector cells, such as lymphocytes, eosinophils, and basophils. How the interaction of various mediators and cells results in anaphylaxis is not fully understood. Objective: To evaluate changes in platelet-activating factor (PAF), platelet-activating factor acetylhydrolase (PAF-AH), tryptase, eosinophils, basophils, and eosinophil cationic protein (ECP) in cashew nut-induced anaphylaxis. Methods: Open cashew nut challenges were performed on 106 children (aged 1-16 years), sensitized to cashew nut, with earlier allergic reaction to cashew nut or no known exposure. PAF, PAF-AH, tryptase, ECP, eosinophils, and basophils were measured at four timepoints. Results: 34/72 (47%) positive challenges were defined as anaphylactic. Eosinophil count decreased progressively during an anaphylactic reaction at all four timepoints (P< .005*) compared to baseline. Although significant PAF elevation was observed 1 hour from moderate-to-severe reaction (P= .039*), PAF seemed to peak especially in anaphylaxis but did not achieve statistical significance. PAF peak ratio (peak PAF/baseline PAF) was significantly greater in anaphylactic reactions compared to the no-anaphylaxis group (P= .008*). Maximal percentage change in eosinophils revealed negative correlation to severity score and PAF peak ratio (Spearman's rho -0.424 and -0.516, respectively). Basophils decreased significantly in moderate-to-severe reactions and in anaphylaxis (P< .05*) compared to baseline. Delta-tryptase (peak tryptase minus baseline) did not differ significantly between anaphylaxis and the no-anaphylaxis subgroups (P= .05). Conclusion: PAF is a specific anaphylaxis biomarker. Marked decline of eosinophils during anaphylaxis may be related to robust secretion of PAF reflecting migration of eosinophils to target tissues. https://doi.org/10.1016/j.anai.2023.04.014