Expression, purification, characterization, and patient IgE reactivity of new macadamia nut iso-allergen.
Structural and functional information about food allergens is essential for understanding the allergenicity of food proteins. All allergens belong to a small number of protein families. Various allergens from different families have been successfully produced recombinantly in E. coli for their characterization and applications in allergy diagnosis and treatment. However, recombinant hexameric 11S seed storage protein has not been reported, although numerous 11S legumins are known to be food allergens, including the recently identified macadamia nut allergen Mac i 2. Here we report the production of a macadamia nut legumin by expressing it in E. coli with a substrate site of HRV 3C protease and cleaving the purified protein with HRV 3C protease. The protease divided the protein into two chains and left a native terminus for the C-terminal chain, resulting in a recombinant hexameric 11S allergen for the first time after the residues upstream to the cleavage site flipped out of the way of the trimer-trimer interaction. The 11S allergens are known to have multiple isoforms in many species. The present study removed an obstacle in obtaining homogeneous allergens needed for studying allergens and mitigating allergenicity. Immunoreactivity of the protein with serum IgE confirmed it to be a new isoform of Mac i 2. https://doi.org/10.1016/j.pep.2022.106211
Food allergen introduction patterns in the first year of life: A US nationwide survey.
Background: Prevention guidelines have changed over the past decade and now recommend the earlier introduction of peanut and egg without delaying the introduction of other food allergens. This paper explored caregiver practices regarding the introduction of food allergens during infancy. Methods: A survey was administered (2021) to a US population-based sample of 3062 caregivers (children 7 months - 3.5 years). Demographics and feeding practices were collected. Weighted frequencies and proportions were calculated using the svyr package in R 4.1. Survey-weighted chi-square statistics and covariate-adjusted, survey-weighted logistic regression models were used for statistical inference. Results: Cow's milk, wheat, and soy were the top three allergens introduced. Peanut and egg were introduced by 17.2% and 15.5% of caregivers before 7 months and 58.8% and 66.4% before 1 year, respectively. The age of peanut and egg introduction differed significantly by race/ethnicity (p < .001) and caregiver age (p < .001). Peanut and egg introduction before 7 months was significantly associated with the increased introduction of other allergenic foods before 1 year (p = <.001; peanut and p = < .001; egg). Caregivers who introduced peanut and egg before 7 months infant age fed an additional mean of 5.4 and 4.5 food allergens, respectively, before 1 year. Few caregivers (0.9%) reported feeding an "early food allergen introduction product" ≥ 3 times, which was significantly associated with parental food allergy (OR = 2.2) and previously seen an allergist (OR = 6.7). Conclusion: More than half of the caregivers are not introducing peanut by age of one year and one-third are not introducing egg, though an observed shift toward earlier peanut and egg introduction was seen in the past 5 years. Peanut and egg introduction seem to co-occur and are associated with increased intake of other food allergens. https://doi.org/10.1111/pai.13896
Oral immunotherapy using boiled peanuts for treating peanut allergy: An open‐label, single‐arm trial.
Background: Peanut allergy affects 1%–3% of children in Western countries. Boiling peanuts has been demonstrated to result in a hypoallergenic product that may provide a safer way of inducing desensitization in peanut-allergic patients by first inducing tolerance to boiled peanut. We aimed to assess the efficacy and safety of oral immunotherapy (OIT) using sequential doses of boiled peanuts followed by roasted peanuts for treating peanut allergy in children. Methods: In this open-label, phase 2, single-arm clinical trial, children aged 6–18 years with a positive history of peanut allergy and positive peanut skin prick test ≥ 8 mm and/or peanut-specific IgE ≥ 15 kU/L at screening underwent OIT involving sequential up-dosing with 12-hour boiled peanut for 12 weeks, 2-hour boiled peanut for 20 weeks and roasted peanut for 20 weeks, to a target maintenance dose of 12 roasted peanuts daily. Primary outcome: proportion of children passing open-label oral food challenge involving cumulative administration of 12 roasted peanuts (12 g peanuts; approximately 3000 mg peanut protein) 6–8 weeks after reaching the target maintenance dose. Secondary outcomes included treatment-related adverse events and use of medications for treating allergy symptoms. Results: Between 1 July 2017 and 22 June 2018, 70 participants were enrolled and commenced OIT. Desensitization was successfully induced in 56 of 70 (80%) participants. Withdrawal due to treatment-related adverse events was infrequent (n = 3). Treatment-related adverse events were reported in 43 (61%) participants, corresponding to a rate of 6.58 per 1000 OIT doses. Medication use associated with treatment-related adverse events was infrequent, with rescue epinephrine use reported by three (4%) participants (0.05 per 1000 doses). Conclusion: Oral immunotherapy using boiled followed by roasted peanuts represents a pragmatic approach that appears effective in inducing desensitization and is associated with a favourable safety profile. https://doi.org/10.1111/cea.14254
Early introduction of peanut reduces peanut allergy across risk groups in pooled and causal inference analyses.
Background: The LEAP study has shown the effectiveness of early peanut introduction in prevention of peanut allergy (PA). In the EAT study, a statistically significant reduction in PA was present only in per-protocol (PP) analyses, which can be subject to bias. Objective: To combine individual-level data from the LEAP and EAT trials and provide robust evidence on the bias-corrected, causal effect of early peanut introduction. Method: As part of the European Union-funded iFAAM project, this pooled analysis of individual paediatric patient data combines and compares effectiveness and efficacy estimates of oral tolerance induction among different risk strata and analysis methods. Results: An intention-to-treat (ITT) analysis of pooled data showed a 75% reduction in PA (p<0.0001) among children randomized to consume peanut from early infancy. A protective effect was present across all eczema severity groups, irrespective of enrolment sensitization to peanut, and across different ethnicities. Earlier age of introduction was associated with improved effectiveness of the intervention. In the pooled PP analysis, peanut consumption reduced the risk of PA by 98% (p<0.0001). A causal inference analysis confirmed the strong PP effect (89% average treatment effect relative risk reduction p<0.0001). A multivariable causal inference analysis approach estimated a large (100%) reduction in PA in children without eczema (p=0.004). Conclusion: We demonstrate a significant reduction in PA with early peanut introduction in a large group of pooled, randomized participants. This significant reduction was demonstrated across all risk subgroups, including children with no eczema. Furthermore, our results point to increased efficacy of the intervention with earlier age of introduction. https://doi.org/10.1111/all.15597
Management of Anaphylaxis During Peanut Oral Immunotherapy.
Background: Peanut oral immunotherapy (POIT) has emerged as an active management option for peanut allergy, with an FDA-approved product now available for therapy. Allergic reactions, including anaphylaxis, can occur during therapy and their management is key in optimizing this treatment and patient outcomes. Purpose of review: In this manuscript, we will review the rates of allergic reactions and anaphylaxis in seminal peanut oral immunotherapy research studies. We will examine factors that can alter the risk of anaphylaxis and describe various strategies, including adjunct therapies, that have the potential to mitigate anaphylaxis risk based on published evidence. Recent findings: Rates of anaphylaxis and epinephrine administration vary in different research studies, but there is consensus that most POIT-related allergic reactions are mild or moderate and not severe. Certain external factors (for example, tiredness, exercise, viral illness) as well as uncontrolled allergic co-morbidities (asthma, allergic rhinitis) have been shown to increase the risk of anaphylaxis during OIT. The search of biomarkers who may predict who is at risk for severe allergic reactions is ongoing. Adjunct therapies have shown promise, but further studies are required to optimize their use alongside POIT. Our understanding of anaphylaxis during POIT has increased in recent years, resulting in better management strategies. However, future plans will need to involve all stakeholders, including physicians, patients and families, researchers, public health authorities, and the food, hospitality, and catering industries. https://doi.org/10.1007/s11882-022-01054-x
Macadamia nut-specific IgE levels for predicting anaphylaxis.
Background: Despite the high risk of anaphylaxis in patients with a macadamia nut allergy (MdA), little is known about the significance of macadamia nut-specific immunoglobulin E (Md-sIgE). Thus, this study aimed to investigate the utility of Md-sIgE for predicting anaphylaxis. Methods: Children with suspected MdA who visited our hospital were included. MdA was defined as either failing the 3-g macadamia nut (Md) oral food challenge (OFC) or confirming obvious immediate symptoms following Md ingestion. Non-MdA was defined as passing the 3-g Md OFC. Results: A total of 41 children (29 [71%] males) with a median age of 7.7 years were included. The median Md-sIgE level was 2.23 kUA /L. Among the 21 children diagnosed with MdA, eight and 13 children did (An group) and did not (non-An group) develop anaphylaxis. Twenty children were included in the non-MdA group. The Md-sIgE level was significantly higher in the An group relative to the others (7.97 vs. 1.92 kUA /L, p < .001). Furthermore, the Md-sIgE level was significantly higher in the An group than in the non-An group (7.97 vs. 1.92 kUA /L, p = .02). However, there was no significant difference in the Md-sIgE between the non-An and non-MdA groups (1.92 vs. 1.90 kUA /L, p > .99). The area under the curve for predicting anaphylaxis in Md-sIgE was 0.92 (95% CI: 0.83-1.00), and the optimal cut-off value was 3.76 kUA /L. Conclusion: Md-sIgE levels were useful in predicting anaphylaxis. Above the cut-off value, we emphasize paying careful attention to the risk of anaphylaxis. https://doi.org/10.1111/pai.13852
Prevalence of Food Allergy in France up to 5.5 Years of Age: Results from the ELFE Cohort.
Background: In France, updated data on food allergies (FAs) are lacking, despite the need for efficient FA management and prevention. This study aimed to evaluate the prevalence of FAs in children in France, describe the most common allergens and determine the prevalence of atopic diseases in children with FAs. Methods: The ELFE study comprises a French nationwide birth cohort, including 18,329 children born in 2011. FAs were assessed by parental reports of food avoidance based on medical advice related to FAs, provided at 2 months and 2, 3.5 and 5.5 years of age. Data regarding FAs were available for 16,400 children. Data were weighted to account for selection and attrition bias. Results: From birth to 5.5 years of age, FAs were reported for 5.94% (95% CI: 5.54-6.34) children. Milk was the most common allergen, followed by egg, peanut, exotic fruits, tree nuts, gluten and fish. Among children with FAs, 20.5% had an allergy to at least two different groups of allergens; 71% reported eczema at least once before 5.5 years of age; 24.4% reported incidence of asthma; and 42.3% reported incidence of allergic rhinitis or conjunctivitis. Conclusion: In France, the prevalence of FAs in children up to 5.5 years of age is approximately 6%. It was demonstrated that 1 in 5 children with allergies had multiple FAs. https://doi.org/10.3390/nu14173624
Efficacy and safety of food allergy oral immunotherapy in adults.
Background: Oral immunotherapy (OIT) is an emerging method for treating food allergy in children. However, data regarding adults undergoing this process are lacking. Methods: We retrospectively analyzed the medical records of patients with food allergy aged ≥17 years who completed OIT treatment between April 2010 and December 2020 at Shamir Medical Center. Data were compared with that of children aged 4 to <11 years and adolescents aged ≥11 to 17 treated during the same time period. Results: A total of 96 adults at a median age of 22.3 years who underwent OIT for milk (n = 53), peanut (n = 18), sesame (n = 7), egg (n = 5), and tree nuts (n = 13) were analyzed and compared with 1299 children and 309 adolescents. Adults experienced more adverse reactions requiring injectable epinephrine, both during in-clinic up-dosing (49% vs. 15.9% and 26.5% for children and adolescents, respectively, p < 0.0001) and during home treatment (22.9% vs. 12.4%, p = 0.007 for children, and 17.5%, p = 0.23 for adolescents). Most adults (61.5%) were fully desensitized, but the rates of full desensitization were significantly lower than children (73.4%, p = 0.013). Significantly more adults (28.3%) undergoing milk OIT failed treatment than children (14.3%, p = 0.015) and adolescents (14.1%, p = 0.022), while failure rates in adults undergoing OIT for other foods were low (9.3%) and comparable with children and adolescents. Conclusions: OIT is successful in desensitizing most adults with IgE-mediated food allergy. Adults undergoing milk OIT are at increased risk for severe reactions and for OIT failure while failure rates in adults undergoing OIT for other foods are low. https://doi.org/10.1111/all.15537
Predictors of anaphylaxis to peanut and tree nuts in a Mediterranean population.
Background: Peanuts (PN) and tree nuts (TN) are major causes of anaphylaxis worldwide. We aimed to determine the clinical and demographic characteristics associated with anaphylaxis in patients sensitized to PN and/or TN in a Mediterranean population. Methods: We conducted a retrospective study, which included 198 patients allergic to PN and/or TN (allergy symptoms plus specific immunoglobulin E [sIgE] sensitization), evaluated in consultations from January 2015 to December 2020. Univariate analysis and multivariate logistic regression models were developed, including demographic, clinical, and laboratory data as independent variables, and anaphylaxis to each PN and/or TN as a dependent variables. Results: Anaphylaxis was associated with an earlier age of onset of allergy to PN, cashew and/or pistachio, and pine nut allergy but not to other TN allergies. Gender, atopic comorbidities, and cofactors were not associated with PN and/or TN anaphylaxis. Anaphylaxis to PN, cashew and/or pistachio, and pine nut were associated with reactivity to a fewer number of PN and/or TN foods. Although sIgE sensitization to lipid transfer proteins (LTP) was highly prevalent in our population, only seed storage protein (SSP) positivity was associated with anaphylaxis in PN allergy. The absence of pathogenesis-related protein family 10 sensitization correlated with PN and hazelnut anaphylaxis. A higher level of sIgE to almond extract predicted anaphylaxis but the level of sIgE to other PN and/or TN extracts did not predict it. Conclusion: The high prevalence of sensitization to the pan-allergen LTP did not seem to have a significant impact in PN and/or TN allergy severity in our study. Instead, other factors, such as early age of onset and positivity for SSPs, seem to strongly associate with anaphylaxis to specific PN and/or TN. These findings may contribute to individual risk assessment in these populations. https://doi.org/10.2500/aap.2022.43.220060
Novel peanut-specific human IgE monoclonal antibodies enable screens for inhibitors of the effector phase in food allergy.
Background: 10% of US residents have food allergies, including 2% with peanut allergy. Mast cell mediators released during the allergy effector phase drive allergic reactions. Therefore, targeting sensitized mast cells may prevent food allergy symptoms. Objective: We used novel, human, allergen-specific, IgE monoclonal antibodies (mAbs) created using human hybridoma techniques to design an in vitro system to evaluate potential therapeutics targeting sensitized effector cells. Methods: Two human IgE mAbs specific for peanut, generated through human hybridoma techniques, were used to sensitize rat basophilic leukemia (RBL) SX-38 cells expressing the human IgE receptor (FcϵRI). Beta-hexosaminidase release (a marker of degranulation), cytokine production, and phosphorylation of signal transduction proteins downstream of FcϵRI were measured after stimulation with peanut. Degranulation was also measured after engaging inhibitory receptors CD300a and Siglec-8. Results: Peanut-specific human IgE mAbs bound FcϵRI, triggering degranulation after stimulation with peanut in RBL SX-38 cells. Sensitized RBL SX-38 cells stimulated with peanut increased levels of phosphorylated SYK and ERK, signal transduction proteins downstream of FcϵRI. Engaging inhibitory cell surface receptors CD300a or Siglec-8 blunted peanut-specific activation. Conclusion: Allergen-specific human IgE mAbs, expressed from human hybridomas and specific for a clinically relevant food allergen, passively sensitize allergy effector cells central to the in vitro models of the effector phase of food allergy. Peanut reproducibly activates and induces degranulation of RBL SX-38 cells sensitized with peanut-specific human IgE mAbs. This system provides a unique screening tool to assess the efficacy of therapeutics that target allergy effector cells and inhibit food allergen-induced effector cell activation. https://doi.org/10.3389/fimmu.2022.974374