Rates of anaphylaxis for the most common food allergies

Effects of Glycosylation Combined with Phosphate Treatment on the Allergenicity and Structure of Tropomyosin in Litopenaeus vannamei

Tropomyosin (TM) is the main allergen in shrimp (Litopenaeus vannamei). In this study, the effects of allergenicity and structure of TM by glycosylation (GOS-TM), phosphate treatment (SP-TM), and glycosylation combined with phosphate treatment (GOS-SP-TM) were investigated. Compared to GOS-TM and SP-TM, the IgG/IgE binding capacity of GOS-SP-TM was significantly decreased with 63.9 ± 2.0 and 49.7 ± 2.7%, respectively. Meanwhile, the α-helix content reduced, surface hydrophobicity increased, and 10 specific amino acids (K30, K38, S39, K48, K66, K74, K128, K161, S210, and K251) were modified by glycosylation on six IgE linear epitopes of GOS-SP-TM. In the BALB/c mice allergy model, GOS-SP-TM could significantly reduce the levels of specific IgE, IgG1, and CD4+IL-4+, while the levels of IgG2a, CD4+CD25+Foxp3+, and CD4+IFN-γ+ were increased, which equilibrated Th1 and Th2 cells, thus alleviating allergic symptoms. These results indicated that glycosylation combined with phosphate treatment can provide a new insight into developing hypoallergenic shrimp food.

Moringa oleifera Leaves Protein Enhances Intestinal Permeability by Activating TLR4 Upstream Signaling and Disrupting Tight Junctions

Changes in intestinal mucosal barrier permeability lead to antigen sensitization and mast cell-mediated allergic reactions, which are considered to play important roles in the occurrence and development of food allergies. It has been suggested that protein causes increased intestinal permeability via mast cell degranulation, and we investigated the effect of camellia Moringa oleifera leaves protein on intestinal permeability and explored its role in the development of food allergies. The current study investigated the effect of M. oleifera leaves protein on intestinal permeability through assessments of transepithelial electrical resistance (TEER) and transmembrane transport of FITC-dextran by Caco-2 cells. The expression levels of Toll-like receptor 4 (TLR4), IL-8, Occludin, Claudin-1, and perimembrane protein family (ZO-1) were detected by real-time PCR and Western blotting. The effect of M. oleifera leaves protein on intestinal permeability was verified in mice in vivo. The serum fluorescence intensity was measured using the FITC-dextran tracer method, and the expression of tight junction proteins was detected using Western blotting. The results showed that M. oleifera leaves protein widened the gaps between Caco-2 cells, reduced transmembrane resistance, and increased permeability. This protein also reduced the mRNA and protein levels of Occludin, Claudin-1, and ZO-1. Animal experiments showed that intestinal permeability was increased, and that the expression of the tight junction proteins Occludin and Claudin-1 were downregulated in mice. This study shows that M. oleifera leaves protein has components that increase intestinal permeability, decrease tight junction protein expression, promote transmembrane transport in Caco-2 cells, and increase intestinal permeability in experimental animals. The finding that M. oleifera leaves active protein increases intestinal permeability suggests that this protein may be valuable for the prevention, diagnosis, and treatment of M. oleifera leaves allergy.

Immunoglobulin E Epitope Mapping and Structure-Allergenicity Relationship Analysis of Crab Allergen Scy p 9

Filamin C is an allergen of Scylla paramamosain (Scy p 9), and six IgE linear epitopes of the allergenic predominant region had previously been validated. However, the IgE epitope and structure-allergenicity relationship of Scy p 9 are unclear. In this study, a hydrophobic bond was found to be an important factor of conformation maintaining. The critical amino acids in the six predicted conformational epitopes were mutated, and the IgE-binding capacity and surface hydrophobicity of four mutants (E216A, T270A, Y699A, and V704A) were reduced compared to Scy p 9. Ten linear epitopes were verified with synthetic peptides, among which L-AA187-205 had the strongest IgE-binding capacity. In addition, IgE epitopes were mapped in the protruding surface of the tertiary structure, which were conducive to binding with IgE and exhibited high conservation among filamin genes. Overall, these data provided a basis for IgE epitope mapping and structure-allergenicity relationship of Scy p 9.

IgE Epitope Analysis and Hypo-Immunoreactivity Derivative of Arginine Kinase in Mantis Shrimp (Oratosquilla oratoria)

As the main allergenic food, shrimp can trigger allergic reactions in various degrees. In this study, arginine kinase (AK) was identified as an allergen in Oratosquilla oratoria by LC-MS/MS. The open reading frame of AK was obtained, which included 356 amino acids, and recombinant AK (rAK) was expressed in Escherichia coli. The results of immunological analysis and circular dichroism showed that rAK displayed similar IgG-/IgE-binding activity and structure as native AK. Besides, five IgE linear epitopes of AK were verified by serological analysis, on the basis of which an epitope-deleted derivative was obtained and named as mAK-L. It has been shown that mAK-L displayed hypo-immunoreactivity compared to rAK, and the contents of secondary structures were different. In conclusion, these discoveries enrich the overall understanding of crustacean allergens and epitopes and set the foundations for food allergy diagnosis and immunotherapy.

Impact of Reaction Setting on the Management, Severity, and Outcome of Pediatric Food-Induced Anaphylaxis: A Cross-Sectional Study

BACKGROUND

Prompt epinephrine autoinjector (EAI) use is the primary treatment for anaphylaxis. However, limited Canadian data exist on the impact of reaction location on EAI use for food-induced anaphylaxis (FIA).

OBJECTIVE

We sought to investigate the setting, management, and severity of pediatric FIA.

METHODS

We recruited children presenting with FIA from 11 Canadian emergency departments. Patient demographics and the setting, management, and symptoms of FIA were collected by standardized questionnaire. Factors associated with prehospital EAI use and reaction severity were determined by logistic regression.

RESULTS

We recruited 3,604 children; 60.2% were male and the median age was 5.0 years (interquartile range 1.8-11.0). Among cases with a known location of FIA (85.0%), home was the most common setting (68.1%), followed by school/daycare (12.8%), other locations (11.4%; eg, park, car), and restaurants (7.4%). In the prehospital setting, EAI was administered in 36.7% of reactions at home, 66.7% in school/daycare, 40.2% in other locations, and 44.5% in restaurants. Relative to reactions occurring at school/daycare, prehospital EAI use was less likely at home (adjusted odds ratio [aOR] 0.80; 95% CI 0.76-0.84), in restaurants (aOR 0.81; 95% CI 0.75-0.87), and in other settings (aOR 0.77; 95% CI 0.73-0.83), when data were adjusted for reaction severity, sex, age, comorbidities, and province. The FIA setting was not associated with reaction severity or hospitalization.

CONCLUSIONS

Prehospital EAI use was higher at school/daycare than in other settings, potentially owing to the presence of policies and training on FIA. Setting-specific interventions including educational programs and policies/laws mandating training and stocking an EAI may improve anaphylaxis recognition and treatment.

Bridging Knowledge Gaps in Anaphylaxis Management Through a Video-Based Educational Tool

Introduction: We aimed to develop and test the effectiveness of an education tool to help pediatric patients and their families better understand anaphylaxis and its management, and to improve current knowledge and treatment guidelines adherence. Methods: From June 2019 to May 2022, 128 pediatric patients with history of food-triggered anaphylaxis who presented to the allergy outpatient clinics at the study institution were recruited. Consenting families were asked to complete 6 questions related to the triggers, recognition, and management of anaphylaxis at the time of presentation to the clinic. Participants were shown a 5-min animated video on the causes, presentation, and management of anaphylaxis. At the end of the video, the participants were redirected to the same 6 questions to respond again. The scores were recorded in proportion of correct answers (minimum 0.0; maximum 1.0). Results: The mean age of the patients was 5.8 ± 4.5 years (range: 0.5-18.8 years). The majority were males (70 patients; 54.7%). The mean baseline prevideo education questionnaire score was 0.76 ± 0.2 (range: 0.3-1.0), whereas the mean follow-up score was 0.82 ± 0.2 (range: 0.3-1.0). This score difference of 0.06 was statistically significant (P < 0.001). There were no significant associations between change in scores and age or gender of the participants. Conclusion: Our video teaching method was successful in educating patients and their families to better understand anaphylaxis and its management at the moment of the clinical encounter. Retention of knowledge at long-term follow-up should be assessed.

Overview of registries for anaphylaxis: a scoping review

OBJECTIVE

This review aimed to describe the scope and operational features of anaphylaxis registries, and to assess their contribution to improving knowledge of anaphylaxis and care of patients who experience anaphylaxis by measuring their research output.

INTRODUCTION

Structured data collection and reporting systems, such as registries, are needed to better understand the burden of anaphylaxis and to protect the growing number of patients with severe allergy. There is a need to characterize current anaphylaxis registries to identify their value in anaphylaxis surveillance, management, and research. Information synthesized in this review will provide knowledge on benefits and gaps in current registries, which may inform the implementation and global standardization of future anaphylaxis reporting systems.

INCLUSION CRITERIA

This scoping review considered literature describing registries worldwide that enroll patients who have experienced anaphylaxis. Published and gray literature sources were included if they described the scope and operational features of anaphylaxis registries.

METHODS

This review followed the JBI methodology for scoping reviews. Embase, MEDLINE, Scopus, and CINAHL were searched for relevant articles. Identified keywords and index terms were adapted for searches of gray literature sources, using Google advanced search functions. Only full-text studies in English were considered for inclusion. Two independent reviewers conducted title and abstract screening and those that did not meet the inclusion criteria were excluded. The full text of potentially relevant articles were retrieved; full-text screening and data extraction were also conducted by two independent reviewers. Any discrepancies were resolved through discussion or with a third reviewer. Tables and a narrative summary were used to describe and compare the scope and features (eg, inclusion criteria, patient demographics, clinical symptoms) of the identified anaphylaxis registries, and to outline their output to assess their contribution to research and clinical practice for anaphylaxis.

RESULTS

A total of 77 full-text publications and eight gray literature sources were used to extract data. The literature search identified 19 anaphylaxis registries, with sites in 28 countries including Europe, the United Kingdom, Canada, the United States, Korea, and Australia. The main purposes of the identified registries were to collect clinical data for research; provide clinical support tools to improve patient care; and operate as allergen surveillance systems to protect the wider community with allergies. Differences in inclusion and health care settings exist, with 11 collecting data on anaphylaxis of any cause, two on food reactions alone, three on fatal anaphylaxis, one on perioperative anaphylaxis, and two on allergic reactions (including anaphylaxis). Five registries enroll cases in allergy centers, five in hospital settings, one in schools, and others target a combination of general practitioners, specialists in emergency departments, and other relevant hospital departments and allergy outpatient clinics. Only three registries operate under a mandatory framework. A total of 57 publications were considered research outputs from registries. All registries except two have published studies from collected data, with the greatest number of articles published from 2019 to the present. Publications mostly addressed questions regarding demographic profile, causes and cofactors, severity, fatal reactions, and gaps in management.

CONCLUSIONS

This review demonstrated that anaphylaxis registries differ in their scope and operation, having been established for different purposes. Importantly, registries have contributed significantly to research, which has highlighted gaps in anaphylaxis management, provoking allergens, and informed targets for prevention for severe and fatal events. Beyond this, registries relay information about anaphylaxis to clinicians and regulatory bodies to improve patient care and protect the community. The ability to link registry data with other health datasets, standardization of data across registries, and incorporation of clinical care indicators to promote quality health care across the health system represent important targets for future systems.

Probabilistic risk assessment for milk in dark chocolate, cookies and other baked goods with PAL sold in Canada

The risk of having an allergic reaction in milk-allergic individuals consuming products with precautionary allergen labelling (PAL) for milk has been rarely studied in products such as dark chocolate, cookies, and other baked goods. A probabilistic risk assessment model was developed to estimate potential risks. Milk occurrence and contamination levels were reported in a previous article from our group. Dose-response curves for milk were constructed using values (n = 1078) from published double-blind placebo-controlled food challenges. Canadian consumption data was extracted from a national survey, and a homemade survey involving food-allergic Canadians. Milk eliciting doses (ED) were 0.23 (ED₀₁), 1.34 (ED₀₅), 3.42 (ED₁₀), and 16.3 (ED₂₅) mg of milk protein (Log-Normal distribution). Average exposures, per eating occasion, were 24 mg (dark chocolate), 3.9 mg (baked goods), and 0.20 mg (cookies) of milk proteins. The estimated risk of having a milk-induced allergic reaction by consuming foods with PAL for milk was higher for dark chocolate (16%; 15,881/100,000) than baked goods (3.8%; 3802/100,000) or cookies (0.6%; 646/100,000) in milk-allergic Canadians. Dark chocolate, cookies, and baked goods with PAL for milk, should be avoided by milk-allergic Canadians (consuming or not products with PAL) to prevent allergic reactions.

Community Use of Epinephrine for the Treatment of Anaphylaxis: A Review and Meta-Analysis

BACKGROUND

Community use of epinephrine for the treatment of anaphylaxis is low. Knowledge of rates of epinephrine use in the pre-hospital setting along with identification of barriers to its use will contribute to the development of policies and guidelines.

OBJECTIVES

A search was conducted on PubMed and Embase in April 2020. Our systematic review focused on 4 domains: (1) epinephrine use in the pre-hospital setting; (2) barriers to epinephrine use in the pre-hospital setting; (3) cost evaluation and cost-effectiveness of epinephrine use; and (4) programs and strategies to improve epinephrine use during anaphylaxis.

METHODS

Two meta-analyses with logit transformation were conducted to: (1) calculate the pooled estimate of the rate of epinephrine use in the pre-hospital setting among cases of anaphylaxis and (2) calculate the pooled estimate of the rate of biphasic reactions among all cases of anaphylaxis.

RESULTS

Epinephrine use in the pre-hospital setting was significantly higher for children compared with adults (20.98% [95% confidence interval (CI): 16.38%, 26.46%] vs 7.17% [95% CI: 2.71%, 17.63%], respectively, P = .0027). The pooled estimate of biphasic reactions among all anaphylaxis cases was 3.92% (95% CI: 2.88%, 5.32%). Our main findings indicate that pre-hospital use of epinephrine in anaphylaxis remains suboptimal. Major barriers to the use of epinephrine were identified as low prescription rates of epinephrine autoinjectors and lack of stock epinephrine in schools, which was determined to be cost-effective. Finally, in reviewing programs and strategies, numerous studies have engineered effective methods to promote adequate and timely use of epinephrine.

CONCLUSION

The main findings of our study demonstrated that across the globe, prompt epinephrine use in cases of anaphylaxis remains suboptimal. For practical recommendations, we would suggest considering stock epinephrine in schools and food courts to increase the use of epinephrine in the community. We recommend use of pamphlets in public areas (ie, malls, food courts, etc.) to assist in recognizing anaphylaxis and after that with prompt epinephrine administration, to avoid the rare risk of fatality in anaphylaxis cases.

Hypoallergenic mutants of the major oyster allergen Cra g 1 alleviate oyster tropomyosin allergenic potency

Design of hypoallergen with low IgE reactivity is desirable for allergen-specific immunotherapy. Despite oyster tropomyosin (Cra g 1) is considered as the major allergen, no immunotherapy is available now. In the current research, we generated hypoallergens of Cra g 1 and evaluated their allergenicity. Four hypoallergenic derivatives were constructed by epitope deletion or site-directed mutagenesis on grounds of the identified epitopes. They showed obvious reduction in reactivity towards IgE from oyster-allergic patients and Cra g 1-sensitized BN rats, as well as significant decrease in degranulation and secretion of allergic mediators including histamine, IL-4, IL-6 and TNF-α. In addition, to further investigate the molecular mechanism, we examined the effects of these variants on FcεRI-dependent signalling pathway in IgE-challenged RBL-2H3 cells. We found that the hypoallergenic mutants were able to attenuate FcεRI-mediated signaling cascades in tested cells. These results indicate that the hypoallergenic molecules have ideal characteristics and offer a promising new strategy in clinical immunotherapy for shellfish-allergic subjects.