(454b) Inhibition of Peanut Induced Mast Cell Degranulation By Designing Covalent Heterobivalent Inhibitors

Food allergy, Type I Hypersensitivity, is induced by abnormal immune responses from immune cells by recognizing food proteins and releasing inflammatory molecules, such as histamine and cytokines. Food allergy specific immunoglobulin E (sIgE) bound to Fc epsilon receptor I (FcεRI) on mast cells are crosslinked by multivalently interacting with food proteins and begin cellular degranulation which may cause detrimental immune responses such as anaphylactic shock. Several first line treatments are available for allergies such as anti-histamine, but they only prevent allergic reactions after the symptoms have occurred and induce numerous side effects, such as immunosuppression. To develop therapeutics that can cure allergic reactions, it is important to target sIgEs so that it prevents crosslinking of sIgEs by allergen protein which eventually inhibits cellular degranulation. Several efforts have been made in the past to design inhibitors regarding this aspect, but it has not been successful because the major challenges for therapies that specifically inhibit sIgEs are to identify the immunogenic epitopes presented on sIgE binding allergen proteins and offset the high sIgE-allergen affinity. Past research has identified several epitopes from allergen proteins via microarray, but these studies only evaluated the binding of epitopes to sIgE, not whether the epitopes activate sIgE-dependent immune responses. Here, we present a synthetic liposomal allergen, we call nanoallergens, that enables the identification of crucial immunogenic sIgE binding epitopes and the development of inhibitors, termed covalent heterobivalent inhibitors (cHBI). Utilizing identified immunodominant epitopes, cHBIs selectively and irreversibly bind to sIgE to prevent allergic reactions. Using sixteen peanut allergy patient sera, we evaluated the most immunodominant epitopes from major peanut proteins, Arah2 and Arah6, via nanoallergens and designed cHBI that permanently inhibits the crucial sIgEs for peanut allergies. We demonstrated a complete inhibition of degranulation responses utilizing a combination of two cHBI via in vitro degranulation assays and ex vivo basophil activation test. This study presents promising preclinical data that further development and assessment of cHBI can be potential therapeutics to prevent food allergies.