Giangrieco, Ivana (2011) STUDY OF PROTEINS AND PEPTIDES FROM PLANT FOODS AND THEIR POSSIBLE EFFECTS ON HUMAN HEALTH. [Tesi di dottorato] (Unpublished)

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Foods can affect human health beyond basic nutritional effects. In fact, foods are a source of different molecules, including nutraceuticals, i.e. health-promoting molecules, and proteins that can cause allergic reactions. The objectives of this thesis are in the framework of a research program focused on the study of allergens and nutraceuticals from plant foods and their possible effects on human health. Kiwifruit has been chosen as a model of food endowed with beneficial effects on human health and also an important source of food allergy, although for comparative purposes other foods have sometimes been included in the study. Four new allergens have been identified in plant food, namely green and gold kiwifruit, black mulberry and tomato. They belong to the family of Lipid Transfer Proteins (LTP) and three of them have already been included in the official list of allergens of the World Health Organization/International Union of Immunological Societies (WHO/IUIS) with the allergen names Act d 10, Act c 10 and Mor n 3. The structural properties of these allergens have been characterized using classical biochemical methodologies. The immunological and clinical features have been investigated using both classical methodologies, such as skin prick test, prick by prick test and DBPCFC, and emerging methodologies, such as the high throughput ISAC system allowing analysis by multiplex biochip-based immunoassay. The results obtained by comparative analysis show a heterogeneous behavior of different LTPs indicating that the biochemical grouping of allergens can be misleading in the allergy diagnosis and that an improved allergy diagnosis can be obtained by testing every single patient with the most comprehensive panel of available LTPs/allergens . The influence of different experimental conditions on the structural properties and IgE reactivity of the kiwifruit allergen kiwellin (Act d 5) was investigated by circular dichroism, skin testing, immunoblotting and ISAC microarray system. Results obtained demonstrated that the physico-chemical features of the environment can affect the conformation and the IgE reactivity of Act d 5. This behavior suggests that the environmental conditions may affect the response of allergy diagnostic systems by modulating the pattern of exposed antigenic epitopes. The functional characterization of kissper, a naturally occurring kiwifruit peptide, performed by immunohystochemical and ELISA experiments on human colonic mucosa deriving from biopsy carried out on subjects suffering from Crohn’s desease, clearly indicated an antinflammatory effect of this molecule. This result suggests a possible use of kissper as a nutraceutical molecule in the treatment of inflammation.

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