Allergenicity and cross-reactivity of Senecio pollen: identification of novel allergens using the immunoproteomics approach

Identification of Allergenic Proteins in Velvet Mesquite (Prosopis velutina) Pollen: An Immunoproteomics Approach

Velvet mesquite (Prosopis velutina) is a native legume of the southwestern United States and northwestern Mexico, contributing significantly to the desert ecosystem and playing key ecological roles. It is also an important cause of allergic respiratory disease widely distributed in the Sonoran, Chihuahuan, and Mojave Deserts. However, no allergens from velvet mesquite pollen have been identified to date. Pollen proteins were extracted and analyzed by one- and two-dimensional electrophoresis and immunoblotting using a pool of 11 sera from mesquite-sensitive patients as the primary antibody. IgE-recognized protein spots were identified by mass spectrometry and bioinformatics analysis. Twenty-four unique proteins, including proteins well known as pollen, food, airway, or contact allergens and four proteins not previously reported as pollen allergens, were identified. This is the first report on allergenic proteins in velvet mesquite pollen. These findings will contribute to the development of specific diagnosis and treatment of mesquite pollen allergy.

Immunoproteomic identification of allergenic proteins in pecan (Carya illinoinensis) pollen

Pecan (C. illinoinensis) pollen is an important cause of allergic respiratory disease. Pecan is distributed worldwide as shade, ornamental or cultivation tree. To date three well known pecan food allergens have been reported, however, pollen allergens have not been identified. Here, we describe the first identification of IgE recognized pecan pollen proteins, for which proteins were analyzed by 2-DE and immunoblotting using a pool of 8 sera from pecan sensitive patients as primary antibody. IgE recognized protein spots were analyzed by LC-MS/MS and identified using a database of translated protein sequences obtained by the assembly of C. illinoinensis public transcriptomic information. This study has identified 17 IgE binding proteins from pecan pollen including proteins widely recognized as allergens and panallergens. These findings will contribute to develop specific diagnosis and treatment of pecan pollen allergy. SIGNIFICANCE: Pecan is a tree highly valued for its fruits that have a great commercial value. To date three pecan seed storage proteins have been officially recognized by the WHO/IUIS allergen nomenclature subcommittee as food allergens (Car i 1, Car i 2 and Car i 4). Pecan tree pollen is highly allergenic and a clinically relevant cause of allergies in North America (USA and Mexico) and regions where the tree is extensively cultivated (Israel, South Africa, Australia, Egypt, Peru, Argentina, and Brazil). Here, we describe the first identification of IgE recognized pollen proteins using an immunoproteomics approach and a protein database created by the assembly of pecan public transcriptomic information. The findings described here will allow the development of new diagnostic and therapeutic modalities for pecan pollen allergy.

Simulated gastrointestinal digestion reduces the allergic reactivity of shrimp extract proteins and tropomyosin

Shrimp are highly allergenic foods. Current management are limited to the avoidance of foods. Therefore, there is an unmet need for a safe and effective therapy using modified allergens. This study focuses on assessing the potential for modification of the allergenicity of shrimp proteins following heat treatment or simulated gastric digestion. Shrimp proteins do not reduce their IgE reactivity after heat treatment but it is reduced by simulated gastric digestion in a time- and dose-dependent manner. Tropomyosin in shrimp extract is worse digested than purified tropomyosin. After 60 min of 10 U/μg pepsin digestion, a strong inhibition was produced in the in vivo skin reactivity of shrimp extracts and in activation of basophils from allergic patients. Immunisation experiments performed in rabbits demonstrated that digested boiled shrimp extract is able to induce IgG antibodies that block the IgE binding to the untreated boiled shrimp extract in shrimp-allergic patients. Building on our observations, digestion treatment could be an effective method for reducing shrimp allergenicity while maintaining the immunogenicity.

Serum antibody signature directed against Candida albicans Hsp90 and enolase detects invasive candidiasis in non-neutropenic patients

Invasive candidiasis (IC) adds significantly to the morbidity and mortality of non-neutropenic patients if not diagnosed and treated early. To uncover serologic biomarkers that alone or in combination could reliably detect IC in this population, IgG antibody-reactivity profiles to the Candida albicans intracellular proteome were examined by serological proteome analysis (SERPA) and data mining procedures in a training set of 24 non-neutropenic patients. Despite the high interindividual molecular heterogeneity, unsupervised clustering analyses revealed that serum 22-IgG antibody-reactivity patterns differentiated IC from non-IC patients. Univariate analyses further highlighted that 15 out of the 22 SERPA-identified IgG antibodies could be useful candidate IC biomarkers. The diagnostic performance of one of these candidates (anti-Hsp90 IgG antibodies) was validated using an ELISA prototype in a test set of 59 non-neutropenic patients. We then formulated an IC discriminator based on the combined immunoproteomic fingerprints of this and another SERPA-detected and previously validated IC biomarker (anti-Eno1 IgG antibodies) in the training set. Its consistency was substantiated using their ELISA prototypes in the test set. Receiver-operating-characteristic curve analyses showed that this two-biomarker signature accurately identified IC in non-neutropenic patients and provided better IC diagnostic accuracy than the individual biomarkers alone. We conclude that this serum IgG antibody signature directed against C. albicans Hsp90 and Eno1, if confirmed prospectively, may be useful for IC diagnosis in non-neutropenic patients.

New shrimp IgE-binding proteins involved in mite-seafood cross-reactivity

SCOPE

Shrimp is a seafood consumed worldwide and the main cause of severe allergenic reactions to crustaceans. Seafood allergy has been related to mite sensitization, mainly mediated by tropomyosin, but other proteins could be involved. The aim of the study was to identify new shrimp allergens implicated in mite-seafood cross-reactivity (CR) in two different climate populations: dry and humid climates.

METHODS AND RESULTS

Shrimp and mite IgE-binding profiles of patients from continental dry and humid climates were analyzed by immunoblotting, and the most frequently recognized Solenocera melantho shrimp proteins were identified by MS as α-actinin, β-actin, fructose biphosphate aldolase, arginine kinase, sarcoplasmic calcium-binding protein, and ubiquitin. Using inhibition immunoblot assays, we demonstrate that tropomyosin and ubiquitin were responsible for mite-seafood CR from both climates; but also α-actinin and arginine kinase are implicated in dry- and humid-climate populations, respectively. Reciprocal inhibition assays demonstrated that mites are the primary sensitizer in humid-climate, as shrimp is in continental dry-climate population.

CONCLUSION

Several new shrimp allergens have been identified and should be considered in the diagnosis and treatment of shrimp allergy and mite-seafood CR. Differences in mite-seafood CR were founded to be based on the climate.

Immunoproteomics analysis of food allergens

Immunoblot-coupled proteomics based on two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), namely, immunoproteomics, has been used for comprehensive identification of food allergens, because it is a simple and inexpensive tool for rapid identification of several IgE-binding proteins. In this section, we describe our protocols for identification of food allergens using immunoproteomics and discuss a few technical points in detail.

Tropomyosin IgE-positive results are a good predictor of shrimp allergy

BACKGROUND

Shrimp is a common cause of food allergy. Our aims were to determine the value of IgE antibodies in the diagnosis of shrimp allergy and to study red shrimp (Solenocera melantho) tropomyosin both as a new allergen and as a cross-reactive IgE-binding protein.

METHODS

We have studied 45 subjects. Skin prick test (SPT) was carried out in all subjects, and specific IgE (sIgE) to shrimp, recombinant and natural shrimp tropomyosins rPen a 1 and nPen m 1, recombinant Der p 10, and Dermatophagoides pteronyssinus was assessed by fluoroimmunoassay and/or immunoblotting. Double-blind, placebo-controlled food challenges were carried out to confirm diagnosis of shrimp allergy. Also, in vitro inhibition tests were performed to evaluate cross-reactivity.

RESULTS

Shrimp allergy was confirmed in 18 shrimp-allergic patients. Skin prick test and IgE antibodies to shrimp were positive in all shrimp-allergic patients; sIgE to rPen a 1 was detected in 98% of these patients. Of the 18 shrimp-tolerant patients, 61% had positive SPT to shrimp, 55% were IgE-positive to shrimp, and 33% showed IgE antibodies to rPen a 1. Determination of IgE to rPen a 1 yielded a positive predictive value of 0.72 and a negative predictive value of 0.91.

CONCLUSION

IgE levels to rPen a 1 provided additional value to the diagnosis of shrimp allergy. Some allergens in mite extract are recognized by patients who are allergic to shrimp, though their clinical relevance remains unknown.

Application of proteomics in asthma research

Bronchial asthma is caused by allergic airway inflammation, resulting in reversible airway obstruction, characterized by airway hyper-responsiveness, bronchoconstriction, increased mucus secretion and an increase in lung vessel permeability. The pathophysiological changes in asthma have been attributed to the altered expression of biologically plausible proteins associated with transcriptional pathways, inflammatory mediators, chemokines, cytokines, apoptosis and cell proliferation. Such multifactorial diseases characteristically involve an interplay of many genetic variations of molecular and biochemical pathways and their interactions with environmental factors. The complex nature of the asthma phenotype, together with genetic heterogeneity and environmental influences, has made it difficult to uncover the aspects that underlie this common disease. Recently, genomic and proteomic technologies have been developed to identify associations between genes, proteins and disease. This approach, called 'omics biology', aims to recognize early onset of disease, institute preventive treatment and identify new molecular targets for novel drugs in multifactorial diseases. This article reviews examples of how proteomic technology can be used to find asthma marker proteins (from the cell model to clinical samples). Identification of protein changes in different stages of asthma could provide further insights into the complex molecular mechanisms involved in this disease. These studies provide new insights for finding novel pathological mediators and biomarkers of asthma.

Evaluation of ash pollen sensitization pattern using proteomic approach with individual sera from allergic patients

BACKGROUND

In Europe, sensitization to ash pollen induces pollinosis with cross-reactivities with other pollen sources. The aim of the study was to identify the repertoire of ash pollen allergens and evaluate the extent of the diversity of the IgE response in ash allergic patients.

METHODS

The IgE reactivities of 114 ash pollen- and eight grass pollen-sensitized patients were screened by 1D immunoblot (SDS-PAGE) against ash pollen extract. The IgE reactivities of 13 ash pollen- and two grass pollen-sensitized patients were then evaluated in 2D immunoblots. Some IgE- and non-IgE-reactive proteins were identified by mass spectrometry.

RESULTS

In 1D analysis, 86% of sera showed binding to Fra e 1 (18-20 kDa), 23% to Fra e 2 (14 kDa), 3% to Fra e 3 (10 kDa) and 57% to High Molecular Weight allergens (HMW, >30 kDa). Individual analysis of 2D immunoblots showed several IgE-binding protein areas among which three were more often recognized: (i) Fra e 1 comprising, at least, 15 isoforms, (ii) a series of acidic spots (45 kDa), and (iii) Fra e 2, the ash profilin. HMW allergens could be resolved in four areas; two unidentified, one homologous to beta-galactosidase and the other to sugar transport proteins. A malate deshydrogenase and calmodulin were shown to be IgE-binding proteins and 10 non-IgE reactive proteins were identified.

CONCLUSIONS

No direct correlation was evidenced between IgE profile and the degree of sensitization even though 2 spectrotypes could be distinguished. Our data contribute to a better delineation of ash pollen allergens and patterns of sensitization.

Developments in the field of allergy in 2008 through the eyes of Clinical & Experimental Allergy

In 2008, many thousands of articles were published on the subject of allergic disease with over 200 reviews, editorials and original papers in Clinical & Experimental Allergy alone. These represent a considerable amount of data and even the most avid reader could only hope to assimilate a small fraction of this knowledge. There is therefore a pressing need for the key messages that emerge from a journal such as Clinical & Experimental Allergy to be summarized by experts in the field in a form that highlights the significance of the developments and sets them in the context of important findings in the field published in other journals. This also has the advantage of making connections between new data in conditions such as asthma, where articles often appear in different sections of the journal. As can be seen from this review, the body of work is diverse both in terms of the disease of interest and the discipline that has been used to investigate it. However, taken as a whole, we hope that the reader will gain a flavour of where the field is mature, where there remain controversies and where the cutting edge is leading.