Biomedical subjects

Erwin L Roggen

Publications and source records attributed to Erwin L Roggen.

7 recordsLinked to original sources

PubMed2006

Investigation on possible allergenicity of 19 different commercial enzymes used in the food industry.

The aim of the study was to investigate the safety to allergic patients of 19 commercially available and authority-approved enzymes used in the food industry. Enzymes produced by genetically modified organisms were included. Four hundred consecutive adult patients with a diagnosed allergy to inhalation allergens, food allergens, bee or wasp were included. All had at least one positive skin prick test to the above allergens. Skin prick testing with the 19 enzymes was performed on the forearm and if positive (in 13 patients), in vitro histamine release from blood basophils were performed. Patients with positive results in skin prick test were subsequently reinvestigated with further purified enzymes and finally challenged orally with the enzymes in a double-blind, placebo-controlled protocol. Only one reaction to a placebo challenge was seen. In some instances a positive skin prick test result or a positive histamine release was seen elicited by the enzymes, but since none of the patients were positive to any of the commercial enzymes in the subsequent oral challenges using exaggerated dosages of the enzymes compared to normal daily intake, the findings are without clinical relevance. A wide variety of enzyme classes and origins was included in the study. Because there were no allergenic findings of clinical relevance it is concluded that ingestion of food enzymes in general is not considered to be a concern with regard to food allergy.

Adult↗

PubMed2006

Respiratory immunotoxicity: an in vitro assessment.

As yet, in vitro assessment of the immunotoxic potency of respiratory agents is not possible. The complexity of the endpoint and the respiratory tract, and the limited availability of well-documented respiratory agents are the main reasons. The evidence that epithelial cells (ECs) are triggered by compounds to express in vitro surface proteins and soluble mediators, has stimulated their use for developing tests for respiratory immunotoxicity. A variety of airway ECs and EC-lines have been assessed, but the available information seems to point at human alveolar cells (e.g., A549) as the most convenient cell type. EC-based test formats with various degrees of complexity have been assessed. Sofar, promising results were obtained using a 3D model using the human A549 lung cell line. Dendritic cells (DCs) have been subjected to intensive research. However, currently available tests are not well suited to discern among the potency of sensitizers. Potential explanations include the lack of standardised protocols for the generation of DCs, no good standards for estimating the quality of in vitro derived DC-cultures, and limited dynamics of the currently used end-points. Alveolar macrophages (AMs) have so far received less attention. This may proof unjustified as macrophages may link innate responses to adaptive immunity. The observation that ECs, DCs and AMs affect each other, suggests that test formats are required combining at least two of these cell types if ranking of compounds according to their sensitising potency is the aim. In addition, the capacity of compounds to cross a cellular membrane is an important property of an immunotoxic compound, which can be assessed only in 3D reconstituted human tissue models. While promising data have been reported for the skin, immunocompetent 3D reconstituted human lung remains to be evaluated for respiratory immunotoxicity. Obviously, the success of any of these simplified test (as compared to the complexity of the immune response) is highly dependent on the availability of early stage biomarkers (expressed at mucosal barrier level) that are predictive for relevant immunotoxicity mechanisms occurring down-stream of the immune response. As yet, such biomarkers are not yet available.

Animals↗

PubMed2006

A novel approach for investigation of specific and cross-reactive IgE epitopes on Bet v 1 and homologous food allergens in individual patients.

BACKGROUND: A clinically relevant allergic reaction requires recognition of at least two different epitopes on the surface of the allergen by IgE. These epitopes may be specific or cross-reactive. Moreover, patterns of IgE reactivity may be patient-specific. The aim of our study was to compare specific and cross-reactive IgE epitopes and epitope patterns between individual patients. We used Bet v 1-related food allergy as a model. METHODS: Five patients were investigated by cross-competitive ELISA for specific and cross-reacting IgE to Bet v 1, and its homologues Gly m 4 (soybean), Ara h 8 (peanut), and Pru av 1 (cherry). Allergen-specific as well as cross-reactive IgE epitopes were assessed by competitive immunoscreening of a phage-displayed random 7-mer peptide library using polyclonal purified IgE from individual sera. The resulting peptide mimics were mapped on the surface of the 3D-structure of the allergens using a computer-based algorithm. RESULTS: Competitive immunoscreening and epitope mapping identified patient-specific IgE epitope patterns. However, one IgE-binding surface area that was recognized by all patients and two recognized by three patients were identified on all four proteins. These results are consistent with the determination of IgE cross-reactivity of the individual patients' sera against the four recombinant allergens by cross-competitive ELISA. CONCLUSIONS: Selection of phage-displayed peptide mimics with serum IgE from allergic patients in combination with computer-based mapping of the peptide mimics onto the surface of the three-dimensional allergen structure is a promising novel tool to investigate IgE epitope specificity in individual patients. Such basic information on epitope structure may be used for prediction of cross-reactivity and potential allergenicity of novel foods.

2S Albumins, Plant↗

PubMed2005

Interactions between dendritic cells and epithelial cells in allergic disease.

Dendritic cells (DCs) play a crucial role in the sensitisation process. Upon encounter with an allergen, DCs require interactions with other cells and factors for triggering a primary or secondary immune response. Epithelial cells (ECs) express features of accessory cells, such as expression of HLA-DR, co-stimulatory molecules, functional FcgammaR, molecules of the antigen-processing machinery, and display an ability to internalise antigen. These features may authorize them to function as immunomodulators (e.g. amplification of memory T cells during secondary immune responses). ECs may increase chemokine (e.g. CCL20) secretion thereby attracting DCs. Epithelial human TSLP activates DC, which allow them to prime naive T cells for the production of pro-inflammatory cytokines, while down-regulating IFN-gamma and IL-10. ECs may also influence the local polarization of types l and 2 antigen-presenting cells via PGE(2) by impairing the ability of maturing DC to produce bioactive IL-12 p70. PGE(2) is synergistic with IL-1beta and TNF-alpha in the induction of functional and phenotypic maturation of DC and induce IL12 p40 production. Sensitisation via the respiratory route may be Th(2) skewed, possibly because the antigen recognition by DC occurs in an environment rich of airway EC-product such as PGE(2).

Cell Line↗

PubMed2004

Isolation of high-affinity human IgE and IgG antibodies recognising Bet v 1 and Humicola lanuginosa lipase from combinatorial phage libraries.

Allergen-specific Fab fragments isolated from combinatorial IgE and IgG libraries are useful tools for studying allergen-antibody interactions. To characterise the interaction between different allergens and antibodies we have created recombinant human phage antibody libraries in the Fab format. Human IgE and IgG libraries have been created from patients allergic to birch pollen or lipase. These libraries have been used to select binders recognising the major birch pollen allergen Bet v 1 and Humicola lanuginosa lipase. A panel of allergen-specific IgE and IgG antibodies were identified; these were further characterised by allergen binding studies using Biacore and competition studies using human sera and antibodies purified from human sera. Affinities in the nM range were recorded and a competition with human sera for allergen binding was observed.

Allergens↗

PubMedDate not supplied

An in silico method using an epitope motif database for predicting the location of antigenic determinants on proteins in a structural context.

Presently X-ray crystallography of protein-antibody complexes is still the most direct way of identifying B-cell epitopes. The objective of this study was to assess the potential of a computer-based epitope mapping tool (EMT) using antigenic amino acid motifs as a fast alternative in a number of applications not requiring detailed information, e.g. development of pharmaceutical proteins, vaccines and industrial enzymes. Using Gal d 4 as a model protein, the EMT was capable of identifying, in the context of the folded protein, amino acid positions known to be involved in antibody binding. The high sensitivity and positive predictive value of the EMT as well as the relevance of the structural associations suggested by the EMT indicated the existence of amino acid motifs that are likely to be involved in antigenic determinants. In addition, differential mapping revealed that sensitivity and positive predictive value were dependent on the minimum relative surface accessibility (RSA) of the amino acids included in the mapping, demonstrating that the EMTs accommodated for the fact that epitopes are three-dimensional entities with various degrees of accessibility. The comparison with existing prediction scales demonstrated the superiority of the EMT with respect to physico-chemical scales. The mapping tool also performed better than the available structural scales, but the significance of the differences remains to be established. Thus, the EMT has the potential of becoming a fast and simple alternative to X-ray crystallography for predicting structural antigenic determinants, if detailed epitope information is not required.

Algorithms↗

PubMedDate not supplied

Towards a consensus on datasets and evaluation metrics for developing B-cell epitope prediction tools.

A B-cell epitope is the three-dimensional structure within an antigen that can be bound to the variable region of an antibody. The prediction of B-cell epitopes is highly desirable for various immunological applications, but has presented a set of unique challenges to the bioinformatics and immunology communities. Improving the accuracy of B-cell epitope prediction methods depends on a community consensus on the data and metrics utilized to develop and evaluate such tools. A workshop, sponsored by the National Institute of Allergy and Infectious Disease (NIAID), was recently held in Washington, DC to discuss the current state of the B-cell epitope prediction field. Many of the currently available tools were surveyed and a set of recommendations was devised to facilitate improvements in the currently existing tools and to expedite future tool development. An underlying theme of the recommendations put forth by the panel is increased collaboration among research groups. By developing common datasets, standardized data formats, and the means with which to consolidate information, we hope to greatly enhance the development of B-cell epitope prediction tools.

Animals↗