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- KUROSE, Kouichi
- Professor
- Research
topics - Development of novel systems for evaluating the allergenicity of food proteins and drugs
- keywords
- Food allergy, Drug allergy
- SHIMAKURA, Kuniyoshi
- Associate Professor
- Research
topics - Study on seafood and Anisakis allergens: identification, biochemical and immunochemical characterization, developing of hypoallergenic strategies, developing of detection or determination methods etc.
- keywords
- Seafood allergens, Anisakis
Allergies are regarded as a problem in many countries of the world. Allergies caused by food, which is essential to human growth and maintenance of life, are called food allergies. The mechanism of action of food allergies is similar to that of typical Type I allergies in most cases, and sufferers have specific immunoglobulin E (IgE) antibodies against substances that trigger the allergic symptoms. The substances are called allergens and the proteins contained in them are the main cause of the allergies in most cases. Although our laboratory is not a medical institution, we believe that studies laying emphasis on causative substances are important for managing allergic problems. In countries consuming large quantities of fishery products, including Japan, there are significant numbers of people who suffer from allergies to fishery products. Therefore, research on allergens relating to fishery products is important from the viewpoint of food hygiene. In addition to fish, shellfish, and mollusks, our laboratory studies allergens from Anisakis, a parasite found in fish.
- ■Development of a novel system for evaluating the allergenicity of low-molecular-weight chemicals such as drugs
- In general, most drugs are not allergenic in their native state because of their low molecular weight. They, however, become allergens if they undergo metabolic activation to chemically reactive forms and then are bound to high-molecular-weight carrier proteins. Allergenicity for human is not necessarily extrapolated from animal studies. Using human monocyte-like cell lines, we are therefore developing an evaluation method to detect drug allergenecity under the consideration of metabolic activation.
- ■Development of a novel system for evaluating the potential allergenicity of food proteins
- We focus on the activation of dendritic cells (DCs), which promote initial sensitization in the early stage of immune response. Using activation signals of DCs as markers of allergenicity that are induced by potential allergens, we are developing a novel system to predict the potential allergenicity of food proteins.
- ■Purification and identification of allergens
- There is no guarantee that only one allergen is contained in a food item. While some sufferers are IgE-positive to multiple proteins in immunoblotting, some are IgE-positive to proteins of different molecular weights from known allergens. Our research involves identifying unknown allergens from extracts obtained from fishery products and purifying them using various kinds of chromatography. We identify the purified allergens by, for example, analyzing partial amino acid sequences of the allergens and checking them against a database, as well as by identifying genes coding for the allergens using a genetic engineering method with primers designed based on the partial sequences, and analyzing the sequences to reveal the complete primary structure.
- ■Elucidation of IgE-binding epitopes
- Allergens and IgE are not randomly bound together; the part of an allergen molecule to which IgE is bound is predetermined. To identify IgE-binding sites (epitopes), we focus on synthetic peptides designed with overlapping amino acid sequences based on amino acid sequence information of allergens and the amino acid residues that are believed to be exposed on the allergen surface from tertiary structure prediction.
- ■Allergen cross-reactivity
- Tropomyosin (TM), a kind of myofibrillar protein, is a major allergen contained in shellfish. In some cases, the IgE that recognizes shellfish TM in allergic individuals also has a positive reaction to TM from mollusks. Although such cross-reactivity is considered to result from similarities in IgE-binding epitopes, this has not been adequately explained. We attempt to elucidate this issue using a scientific approach.
- ■Elucidation of the properties of new allergens
- Sarcoplasmic calcium-binding proteins contained in prawns of the family Penaeidae, paramyosin contained in a certain kind of mollusk, and several kinds of proteins contained in Anisakis have been newly identified as allergens on the basis of our studies. In addition to elucidating IgE epitopes and immunological properties such as cross-reactivity in other species, we investigate chemical properties such as tolerance to digestive enzymes and the influence of changes in temperature or pH on the allergic properties of these newly discovered allergens.
- ■Development of hypoallergenic food
- If allergens are removed from food or denatured so as to not induce antigen-antibody reactions, it leads to the development of hypoallergenic food. At present, protease treatment during the production of extract products has been proven effective. Are there any other effective means of reducing allergenicity? In parallel with investigations into the various properties of allergens, we collect basic data on allergens to create processed fish products that are safe for sufferers.
- ■Mapping of Anisakis allergens using two-dimensional gel electrophoresis and other techniques
- In some cases, sufferers self-diagnosed with fish allergies have IgE that reacts with components originating not from fish but from Anisakis, a parasite found in fish. More than 10 kinds of allergens contained in Anisakis have been identified, and the number and kinds of allergens vary with the sufferers. To construct a simultaneous detection system combining two-dimensional gel electrophoresis and immunoblotting, we assign bands obtained by the electrophoretic separation of Anisakis extract to known allergens.
Genetic analyzer
Analyzer to determine gene arrangement
Example of immunoblotting
Analysis of molecular weight and the number of allergens
Peptide synthesizer
Useful tool for analysis of IgE-binding epitopes
