Characterization of signal sequence derived T-cell epitopes from filamentous fungal allergens

Abstract

Fungal allergy including allergic rhinitis and asthma results from exposure to spores. Airborne fungal spores occur widely and are important causes of allergic respiratory disease worldwide. Many fungi can cause IgE-mediated hypersensitivity in people. The most common allergic fungi belong to the genera Aspergillus, Alternaria, Cladosporium, and Penicillium. Some allergens from these genera have been characterized. Many studies of fungal allergy prevalence, diagnosis, and immunotherapy have been done, while more research is needed to prevent, diagnose and treat fungal allergy. In immunotherapy, patients are desensitized through the administration of increasing doses of allergen that gradually decreases the IgE-dominated response. Subcutaneous immunotherapy is the common route of administration and consists of injections of allergen extract. Fungal extract immunotherapy has been used to treat Alternaria alternata allergy, but requires long term administration and may have potential side effects including anaphylaxis. A safer, more effective, and shorter treatment like peptide immunotherapy is needed for patient desensitization. This thesis covers the current status of some common fungal allergens and the possible use of peptide immunotherapy for fungal allergy. The aim of my study was to characterize potential peptides for immunotherapy from A. alternata and Aspergillus fumigatus. We derived peptides from A. alternata that had several advantages. They are 15 amino acids in length to reduce IgE cross-linking. They are promiscuous for HLA Class II binding to cover large patient populations. They are derived from all known allergens involved in a particular allergic condition, and they are tested with immune cells from actual human trial study population for optimal selection and blending of multiple immunologically active peptides. We predicted Alta a 1 T-cell epitopes using the Pro Pred algorithm. Each peptide contained one or more T-cell epitopes shown to bind one or more Class II MHC molecules by Proimmune assay. For peptide confirmation, IL-4 ELISPOT of Alternaria allergic patient and control peripheral blood mononuclear cells (PBMCs) were conducted. My study analyzed the signal sequence of some allergens of A. alternata and A. fumigatus. The signal sequence region of A. alternata and A. fumigatus allergens was predicted by the SIGNALP algorithm. Allergens with signal sequences were subjected to ProPred analysis to identify T-cell epitopes present and to identify those with high promiscuity to Class II MHC molecules. Multiple peptides were identified that met this criteria. These peptides were submitted for Proimmune analysis and several peptides were found to show in vitro binding to Class II MHC molecules and were thus shown to be strong T-cell epitope candidates. Our results generated potential peptides that could be used for fungal allergy immunotherapy.

Date of Award	31 Dec 2016
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Geoffrey Robson (Supervisor)