Progressive knowledge of allergenic structures resulted in a broad availability of allergenic molecules for diagnosis. Component‐resolved diagnosis allowed a better understanding of patient ...sensitization patterns, facilitating allergen immunotherapy decisions. In parallel to the discovery of allergenic molecules, there was a progressive development of a regulation framework that affected both in vitro diagnostics and Allergen Immunotherapy products. With a progressive understanding of underlying mechanisms associated to Allergen immunotherapy and an increasing experience of application of molecular diagnosis in daily life, we focus in analyzing the evidences of the value provided by molecular allergology in daily clinical practice, with a focus on Allergen Immunotherapy decisions.
Background
Recent studies show that nsLTP sensitization is not limited to the Mediterranean basin and can present diverse clinical phenotypes. It remains challenging to predict clinical outcome when ...specific IgE antibodies (sIgE) to nsLTPs are present. This study compares both clinical and in vitro allergy characteristics but also diagnostic performance of a basophil activation test (BAT) and sIgG4 in nsLTP‐sensitized patients from Antwerp (ANT, Belgium) and Barcelona (BCN, Spain).
Methods
Adult subjects with positive sIgE rPru p 3 and/or rMal d 3 ≥ 0.10 kUA/L (n = 182) and healthy controls (n = 37) were included. NsLTP‐sensitized individuals were stratified according to clinical symptoms with peach/apple, respectively. BAT rPru p 3 and rMal d 3 were performed and sIgG4 antibodies to both components quantified.
Results
In BCN, only ratios of sIgG4/sIgE rMal d 3 and BAT rMal d 3 (0.001 µg/mL) can identify clinically relevant Mal d 3 sensitization (sensitivity of 60%‐63% and a specificity of 75%‐67%, respectively). In ANT, only the sIgE/total IgE rPru p 3 ratio shows added value (sensitivity 60% and specificity 83%). Finally, it appears that symptomatic patients in BCN are more sensitive to lower allergen concentrations compared to ANT. In addition, it was shown that ANT patients were more often sensitized to pollen and that specific pollen sources differed between regions.
Conclusions
NsLTP‐related allergy profiles and diagnostic performance differ significantly between regions and are component‐specific, which makes extrapolation of data difficult to do. In addition, it seems that basophil sensitivity might show geographical differences. Additional research is needed to confirm these findings.
This study explores the performance of BAT, sIgE/total IgE, sIgG4 and sIgG4/sIgE ratio in Pru p 3‐ and Mal d 3‐sensitized populations from Antwerp (ANT) and Barcelona (BCN). In BCN, only ratios of sIgG4/sIgE rMal d 3 and BAT rMal d 3 can identify clinically relevant Mal d 3 sensitization, whereas in ANT, only the sIgE/total IgE rPru p 3 ratio shows added value. NsLTP sensitization and diagnostic performance cannot be extrapolated from one population to another. BAT, basophil activation test; nsLTP, nonspecific lipid transfer protein.
Background
Despite all the efforts made up to now, the reasons that facilitate a protein becoming an allergen have not been elucidated yet. Alt a 1 protein is the major fungal allergen responsible ...for chronic asthma, but little is known about its immunological activity. Our main purpose was to investigate the ligand‐dependent interactions of Alt a 1 in the human airway epithelium.
Methods
Alt a 1 with and without its ligand (holo‐ and apo‐ forms) was incubated with the pulmonary epithelial monolayer model, Calu‐3 cells. Allergen transport and cytokine production were measured. Pull‐down and immunofluorescence assays were employed to identify the receptor of Alt a 1 using the epithelial cell model and mouse tissues. Receptor‐allergen‐ligand interactions were analyzed by computational modeling.
Results
The holo‐form could activate human monocytes, PBMCs, and polarized airway epithelial (Calu‐3) cell lines. The allergen was also transported through the monolayer, without any alteration of the epithelial integrity (TEER). Alt a 1 also induced the production of proinflammatory IL8 and specific epithelial cytokines (IL33 and IL25) by Calu‐3 cells. The interaction between epithelial cells and holo‐Alt a 1 was found to be mediated by the SLC22A17 receptor, and its recognition of Alt a 1 was explained in structural terms.
Conclusions
Our findings identified the Alt a 1 ligand as a central player in the interaction of the allergen with airway mucosa, shedding light into its potential role in the immunological response, while unveiling its potential as a new target for therapy intervention.
Alt a 1 is released from Alternaria alternata spores in complex with its native ligand, being recognized by the Solute carrier family 22 member 17 receptor. Production of cytokines IL25 and IL33 occurs only in the presence of the ligand, being abolished with specific antibodies against Solute carrier family 22 member 17. Alt a 1 shows structural relationship with human siderocalin mimicking its airway entry route.
Although strawberries are highly appreciated fruits, their intake can induce allergic reactions in atopic patients. These reactions can be due to the patient's previous sensitization to the major ...birch pollen allergen Bet v 1, by which IgE generated in response to Bet v 1 cross-reacts with the structurally related strawberry Fra a 1 protein family. Fra a 1.02 is the most expressed paralog in ripe strawberries and is highly allergenic. To better understand the molecular mechanisms regulating this allergic response, we have determined the three-dimensional structure of Fra a 1.02 and four site-directed mutants that were designed based on their positions in potential epitopes. Fra a 1.02 and mutants conform to the START fold. We show that the cross-reactivity of all the mutant variants to IgE from patients allergic to Bet v 1 was significantly reduced without altering the conserved structural fold, so that they could potentially be used as hypoallergenic Fra a 1 variants for the generation of vaccines against strawberry allergy in atopic patients.
Food allergies are recognized as a global health concern. In order to protect allergic consumers from severe symptoms, allergenic risk assessment for well‐known foods and foods containing genetically ...modified ingredients is installed. However, population is steadily growing and there is a rising need to provide adequate protein‐based foods, including novel sources, not yet used for human consumption. In this context safety issues such as a potential increased allergenic risk need to be assessed before marketing novel food sources. Therefore, the established allergenic risk assessment for genetically modified organisms needs to be re‐evaluated for its applicability for risk assessment of novel food proteins. Two different scenarios of allergic sensitization have to be assessed. The first scenario is the presence of already known allergenic structures in novel foods. For this, a comparative assessment can be performed and the range of cross‐reactivity can be explored, while in the second scenario allergic reactions are observed toward so far novel allergenic structures and no reference material is available. This review summarizes the current analytical methods for allergenic risk assessment, highlighting the strengths and limitations of each method and discussing the gaps in this assessment that need to be addressed in the near future.
There is a rising need of additional novel food sources with adequate nutritional value and low health risk. Food allergic consumers develop adverse immune reactions toward nontoxic dietary proteins. Current allergenic‐risk assessment includes extraction and characterization of food proteins and immunological testing for their allergenic activity. The study summarizes the current analytical methods applied and the need for improved allergenic risk assessment for novel foods.
Background
Ole e 7 is a nonspecific lipid transfer protein (nsLTP) from olive pollen, one of the main allergenic pollens worldwide. This allergenic nsLTP is responsible for severe symptoms in regions ...with high olive pollen exposure, where many Ole e 7‐sensitized patients exhibit a co‐sensitization to the peach nsLTP, Pru p 3. However, there is no evidence of cross‐reactivity, which explains this observed co‐sensitization. Therefore, the purpose of this study was to explore the relationship between Ole e 7 and Pru p 3.
Methods
A total of 48 patients sensitized to Ole e 7 and/or Pru p 3 were included in the study. Specific IgE serum levels were measured by ImmunoCAP 250 and ELISA. Inhibition assays were performed to determine the existence of cross‐reactivity between both nsLTPs. Allergic response was analyzed ex vivo (basophil activation test) and in vitro (RBL‐2H3 mast cell model).
Results
Common IgG and IgE epitopes were identified between both allergens. IgE‐binding inhibition was detected in Ole e 7–monosensitized patients using rPru p 3 as inhibitor, reaching inhibition values of 25 and 100%. Ex vivo and in vitro assays revealed a response against rPru p 3 in four (31%) Ole e 7–monosensitized patients.
Conclusions
Our results suggest that Ole e 7 could play a new role as primary sensitizer in regions with high olive pollen exposure, leading to the peach nsLTP sensitization. This co‐sensitization process would occur because of the cross‐reactivity between Ole e 7 and Pru p 3 observed in some allergic patients.
Ole e 7 cross‐reacts with nonspecific lipid transfer proteins (LTPs) from pollen and food, specifically with peach and pear. Common IgG and IgE epitopes were identified between Ole e 7 and Pru p 3 despite their low amino acid sequence identity. Ole e 7 could act as primary sensitizer in regions with high olive pollen exposure, leading to Pru p 3 sensitization.
IgE-mediated allergy to wheat proteins can be caused by exposure through ingestion, inhalation, or skin/mucosal contact, and can affect various populations and age groups. Respiratory allergy to ...wheat proteins is commonly observed in adult patients occupationally exposed to flour, whereas wheat food allergy is more common in children. Wheat allergy is of growing importance for patients with recurrent anaphylaxis, especially when exercise related. The diagnosis of wheat allergy relies on a consistent clinical history, skin prick testing with well-characterized extracts and specific IgE tests. The accuracy of wheat allergy diagnosis may be improved by measuring IgE responses to several wheat components. However, a high degree of heterogeneity has been found in the recognition pattern of allergens among patient groups with different clinical profiles, as well as within each group. Thus, oral provocation with wheat or the implicated cereal is the reference test for the definitive diagnosis of ingested wheat/cereal allergy.
Background
Ingestion of food allergens present in maternal milk during breastfeeding has been hypothesized as a gateway to sensitization to food; however, this process could develop during pregnancy, ...as the maternal–fetal interface develops a Th2‐ and Treg‐mediated environment to protect the fetus. We hypothesized that in these surroundings, unborn children are exposed to food allergens contained in the mother's diet, possibly giving rise to first sensitization.
Methods
The presence of allergens in utero was studied by analyzing amniotic fluid (AF) samples in two different stages of pregnancy: at 15–20 weeks and after delivery at term. An antibody microarray was developed to test for the most common food allergens. The array detects the presence of ten allergens from milk, fruit, egg, fish, nuts, and wheat.
Results
AF from 20 pregnant women was collected: eight after delivery at term and 12 from women who underwent diagnostic amniocentesis between weeks 15 and 20 of gestation. The presence of allergens was detected in all samples. Samples from amniocentesis had a higher allergen concentration than samples after delivery at term.
Conclusions
We demonstrated the presence of intact major food allergens in AF samples. This early contact could explain subsequent sensitization to foods never eaten before.
CD1 molecules present lipid antigens for recognition by T-cell receptors (TCRs). Although a reasonably detailed picture of the CD1-lipid-TCR interaction exists, the initial steps regarding lipid ...loading onto and exchange between CD1 proteins remain elusive. The hydrophobic nature of lipids and the fact that CD1 molecules are unable to extract lipids from membranes raise the need for the assistance of helper proteins in lipid trafficking. However, the experimental study of this traffic in the endosomal compartments at which it occurs is so challenging that computational studies can help provide mechanistic insight into the associated processes. Here we present a multifaceted computational approach to obtain dynamic structural data on the human CD1d isotype. Conformational dynamics analysis shows an intrinsic flexibility associated with the protein architecture. Electrostatic properties together with molecular dynamics results for CD1d complexes with several lipids and helper proteins unravel the high dynamic plasticity of the antigen-binding site that is crucially favoured by acidic pH and the presence of helper proteins.
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