Epithelia and endothelia separate different tissue compartments and protect multicellular organisms from the outside world. This requires the formation of tight junctions, selective gates that ...control paracellular diffusion of ions and solutes. Tight junctions also form the border between the apical and basolateral plasma-membrane domains and are linked to the machinery that controls apicobasal polarization. Additionally, signalling networks that guide diverse cell behaviours and functions are connected to tight junctions, transmitting information to and from the cytoskeleton, nucleus and different cell adhesion complexes. Recent advances have broadened our understanding of the molecular architecture and cellular functions of tight junctions.
There is an increasing demand for animal-derived products in the developing countries. This poses major concerns for the sustainable production of safe and nutritious food. Consequently, to address ...these needs alternative sustainable sources of valuable dietary proteins are sought for.
In this review, we discuss alternative protein sources for human food consumption such as novel foods derived from other animal sources like insects. Before these novel foods can enter the market place, their safety for consumers should be demonstrated. We herein provide an overview of the legislative framework currently in place across Europe, the key elements required for allergenicity assessment of novel foods, the tools at disposal for allergenicity prediction and the most advanced technologies available for food allergen detection and characterization.
Effective characterization of potential protein-based allergenic hazards in novel food ingredients is essential to support effective risk assessment. Development of a cost-effective, validated tool box to allow improved hazard characterization for allergenicity risk assessment is needed. Although novel methodologies, such as mass spectrometry, have great potential for allergen characterization and allergen detection in different food contributing to reduce the risk for allergic consumers, some work is still required for method validation and the creation of protein sequence databases for proteomic analysis.
•Characterization of potential protein-based allergenic hazards in novel food is essential for effective risk assessment.•A cost-effective, validated tool box to improve hazard characterization for allergenicity risk assessment is needed.•Efforts at EU level aim to improve the risk assessment, and develop and harmonize methods for allergenicity prediction.
IgE-mediated allergy to milk and egg is widespread in industrialised countries and mainly affects infants and young children. It may be connected to an incomplete digestion of dietary proteins ...causing an inappropriate immune response in the gut. In order to study this, a biochemical model of infant gastroduodenal digestion has been developed, which has reduced levels of protease (eightfold for pepsin and tenfold for trypsin and chymotrypsin), phosphatidylcholine and bile salts, compared with the adult model. This model has been used to study the behaviour of three characterised food-relevant proteins (bovine β-lactoglobulin (β-Lg), β-casein (β-CN) and hen's egg ovalbumin), all of which are relevant cows' milk and hens' egg allergens. Digestion products were characterised using electrophoresis, immunochemical techniques and MS. These showed that ovalbumin and β-CN were digested more slowly using the infant model compared with the adult conditions. Resistant fragments of β-CN were found in the infant model, which correspond to previously identified IgE epitopes. Surprisingly, β-Lg was more extensively degraded in the infant model compared with the adult one. This difference was attributed to the tenfold reduction in phosphatidylcholine concentration in the infant model limiting the protective effect of this phospholipid on β-Lg digestion.
The unique physiochemical properties of wheat gluten enable a diverse range of food products to be manufactured. However, gluten triggers coeliac disease, a condition which is treated using a ...gluten-free diet. Analytical methods are required to confirm if foods are gluten-free, but current immunoassay-based methods can unreliable and proteomic methods offer an alternative but require comprehensive and well annotated sequence databases which are lacking for gluten. A manually a curated database (GluPro V1.0) of gluten proteins, comprising 630 discrete unique full length protein sequences has been compiled. It is representative of the different types of gliadin and glutenin components found in gluten. An in silico comparison of their coeliac toxicity was undertaken by analysing the distribution of coeliac toxic motifs. This demonstrated that whilst the α-gliadin proteins contained more toxic motifs, these were distributed across all gluten protein sub-types. Comparison of annotations observed using a discovery proteomics dataset acquired using ion mobility MS/MS showed that more reliable identifications were obtained using the GluPro V1.0 database compared to the complete reviewed Viridiplantae database. This highlights the value of a curated sequence database specifically designed to support the proteomic workflows and the development of methods to detect and quantify gluten.
We have constructed the first manually curated open-source wheat gluten protein sequence database (GluPro V1.0) in a FASTA format to support the application of proteomic methods for gluten protein detection and quantification. We have also analysed the manually verified sequences to give the first comprehensive overview of the distribution of sequences able to elicit a reaction in coeliac disease, the prevalent form of gluten intolerance. Provision of this database will improve the reliability of gluten protein identification by proteomic analysis, and aid the development of targeted mass spectrometry methods in line with Codex Alimentarius Commission requirements for foods designed to meet the needs of gluten intolerant individuals.
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•A curated database comprising 630 gluten protein sequences has been compiled.•Sequences represent the gliadin and glutenin protein species found in gluten.•Coeliac toxic motifs were distributed across all gluten protein sub-types.•It gave more reliable identifications than the reviewed Viridiplantae database.
For adults, prevalence estimates of food sensitization (FS) and food allergy (FA) have been obtained in a standardized manner across Europe. For children, such estimates are lacking.
To determine the ...prevalence of self-reported FA, FS, probable FA (symptoms plus IgE sensitization), and challenge-confirmed FA in European school-age children.
Data on self-reported FA were collected through a screening questionnaire sent to a random sample of the general population of 7- to 10-year-old children in 8 European centers in phase I of the EuroPrevall study. Data on FS and probable FA were obtained in phase II, comprising an extensive questionnaire on reactions to 24 commonly implicated foods, and serology testing. Food challenge was performed in phase III.
Prevalence (95% CI) of self-reported FA ranged from 6.5% (5.4-7.6) in Athens to 24.6% (22.8-26.5) in Lodz; prevalence of FS ranged from 11.0% (9.7-12.3) in Reykjavik to 28.7% (26.9-30.6) in Zurich; and prevalence of probable FA ranged from 1.9% (0.8-3.5) in Reykjavik to 5.6% (3.6-8.1) in Lodz. In all centers, most food-sensitized subjects had primary (non–cross-reactive) FS. However, FS due to birch pollen related cross-reactivity was also common in Central-Northern Europe. Probable FA to milk and egg occurred frequently throughout Europe; to fish and shrimp mainly in the Mediterranean and Reykjavik. Peach, kiwi, and peanut were prominent sources of plant FA in most countries, along with notably hazelnut, apple, carrot, and celery in Central-Northern Europe and lentils and walnut in the Mediterranean.
There are large geograhical differences in the prevalence of FS and FA in school-age children across Europe. Both primary and cross-reactive FS and FA occur frequently.
Background Precautionary labeling is used to warn consumers of the presence of unintended allergens, but the lack of agreed allergen thresholds can result in confusion and risk taking by patients ...with food allergy. The lack of data on threshold doses below which subjects are unlikely to react is preventing the development of evidence-based allergen management strategies that are understood by clinician and patient alike. Objective We sought to define threshold dose distributions for 5 major allergenic foods in the European population. Methods Patients with food allergy were drawn from the EuroPrevall birth cohort, community surveys, and outpatient clinic studies and invited to undergo a food challenge. Low-dose, double-blind, placebo-controlled food challenges were undertaken with commercially available food ingredients (peanut, hazelnut, celery, fish, and shrimp) blinded into common matrices. Dose distributions were modeled by using interval-censoring survival analysis with 3 parametric approaches. Results Of the 5 foods used for challenge, 4 produced similar dose distributions, with estimated doses eliciting reactions in 10% of the allergic population (ED10 ), ranging from 1.6 to 10.1 mg of protein for hazelnut, peanut, and celery with overlapping 95% CIs. ED10 values for fish were somewhat higher (27.3 mg of protein), although the CIs were wide and overlapping between fish and plant foods. Shrimp provided radically different dose distributions, with an ED10 value of 2.5 g of protein. Conclusion This evidence base will contribute to the development of reference doses and action levels for allergens in foods below which only the most sensitive subjects might react.
Background
The Learning Early About Peanut allergy (LEAP) study has shown the effectiveness of early peanut introduction in prevention of peanut allergy (PA). In the Enquiring About Tolerance (EAT) ...study, a statistically significant reduction in PA was present only in per‐protocol (PP) analyses, which can be subject to bias.
Objective
The aim of this study was 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 pediatric 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 < .0001) among children randomized to consume peanut from early infancy. A protective effect was present across all eczema severity groups, irrespective of enrollment 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 < .0001). A causal inference analysis confirmed the strong PP effect (89% average treatment effect relative risk reduction p < .0001). A multivariable causal inference analysis approach estimated a large (100%) reduction in PA in children without eczema (p = .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.
An integrated meta‐analysis employing both LEAP (high risk) and EAT (normal risk) individual patient data shows that early introduction of peanut in infancy prevents the development of peanut allergy regardless of presence or severity of eczema, ethnicity and sensitization to peanut. Earlier introduction of peanut before 6 months of age is more effective than later introduction in the prevention of peanut allergy. Causal inference methods accurately estimated the efficacy of this strategy while addressing the problems of poor adherence in the intention‐to‐treat analyses and biases in the per‐protocol analyses.Abbreviations: EAT, enquiring about tolerance; ITT, intention to treat; LEAP, learning early about allergy; PP, per protocol
Background
Allergy can be diagnosed using basophil tests. Several methods measuring basophil activation are available. This study aimed at comparing basophil activation test (BAT), histamine release ...assay (HR), and passive sensitization histamine release assay (passive HR) in the diagnosis of peanut allergy.
Methods
BAT, HR, and passive HR were performed on 11 peanut‐allergic and 14 nonallergic subjects. Blood was incubated with peanut extract or anti‐IgE and tests were performed as follows: BAT—CD63 upregulation was assessed by flow cytometry; HR—released histamine was quantified by a glass fiber‐based fluorometric method; passive HR—IgE‐stripped donor basophils were incubated with participants' serum and histamine release was quantified as HR.
Results
CDsens, a measure of basophil allergen sensitivity, was significantly higher for BAT (80.1±17.4) compared to HR (23.4±10.31) and passive HR (11.1±2.0). BAT, HR, and passive HR had a clinical sensitivity of 100%, 100%, and 82% and specificity of 100%, 100%, and 100%, respectively, when excluding inconclusive results. BAT identified 11 of 11 allergic patients, HR 10, and passive HR 9. Likewise, BAT recognized 12 of 14 nonallergic subjects, HR 10, and passive HR 13. However, the tests' diagnostic performances were not statistically different. Interestingly, nonreleasers in HR but not in BAT had lower basophil count compared to releasers (249 vs 630 counts/min).
Conclusion
BAT displayed a significantly higher CDsens compared to HR and passive HR. The basophil tests' diagnostic performances were not significantly different. Still, BAT could diagnose subjects with low basophil number in contrast to HR.
According to the community-based EuroPrevall surveys, prevalence of self-reported food allergy (FA) in adults across Europe ranges from 2% to 37% for any food and 1% to 19% for 24 selected foods.
To ...determine the prevalence of probable FA (symptoms plus specific IgE-sensitization) and challenge-confirmed FA in European adults, along with symptoms and causative foods.
In phase I of the EuroPrevall project, a screening questionnaire was sent to a random sample of the general adult population in 8 European centers. Phase II consisted of an extensive questionnaire on reactions to 24 preselected commonly implicated foods, and measurement of specific IgE levels. Multiple imputation was performed to estimate missing symptom and serology information for nonresponders. In the final phase, subjects with probable FA were invited for double-blind placebo-controlled food challenge.
Prevalence of probable FA in adults in Athens, Reykjavik, Utrecht, Lodz, Madrid, and Zurich was respectively 0.3%, 1.4%, 2.1%, 2.8%, 3.3%, and 5.6%. Oral allergy symptoms were reported most frequently (81.6%), followed by skin symptoms (38.2%) and rhinoconjunctivitis (29.5%). Hazelnut, peach, and apple were the most common causative foods in Lodz, Utrecht, and Zurich. Peach was also among the top 3 causative foods in Athens and Madrid. Shrimp and fish allergies were relatively common in Madrid and Reykjavik. Of the 55 food challenges performed, 72.8% were classified as positive.
FA shows substantial geographical variation in prevalence and causative foods across Europe. Although probable FA is less common than self-reported FA, prevalence still reaches almost 6% in parts of Europe.
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