(242e) Engineering Hetero-Bivalent Ligands to Inhibit IgE Clustering On Mast Cells in Allergies | AIChE

(242e) Engineering Hetero-Bivalent Ligands to Inhibit IgE Clustering On Mast Cells in Allergies

Authors 

Bilgicer, B. - Presenter, University of Notre Dame
Handlogten, M. - Presenter, University of Notre Dame
Kiziltepe, T. - Presenter, University of Notre Dame


Allergy is a disorder of the immune system which is elicited by the allergen-mediated-clustering of the immunoglobulin E (IgE) molecules on the surface of mast cells and basophils. Allergenic diseases are a major cause of illness and disability in the US, and there is broad consensus that the prevalence of type I allergy is increasing worldwide. The majority of the current therapies used to treat allergy related adverse immunologic responses involve non-specific suppression of parts of the immune system. This results in the increased risk of infectious diseases (i.e. parasitic infections). Development and use of selectively targeted therapeutics would decrease these risks. Multivalent binding interactions provide higher affinity (termed avidity), and result in stronger interactions. Earlier studies have established that bivalent binding, as in the case of antibodies, can strengthen the avidity of an interaction up by six orders of magnitude over monovalent binding. Our overall goal in this project was to engineer hetero-bivalent peptidic ligands that would competitively and selectively inhibit allergen binding to IgEs on mast cells, thereby inhibiting IgE clustering and allergic responses. This was accomplished via designing hetero-bivalent molecules that simultaneously targeted two nearby sites located on the Fab domain of an IgE, the antigen binding site, and the less renowned ?unconventional nucleotide binding site?. Simultaneous bivalent binding to both these sites provided the hetero-bivalent ligand with enhanced avidity and selectivity for the target IgE, and enabled competitive inhibition of allergen binding to the IgEs. These hetero-bivalent ligand were designed to have two moieties ? the antigenic molecule itself, and the ATP analog- covalently linked by a flexible linker molecule. Specifically we have: i) designed and synthesized hetero-bivalent ligands with various linker molecules; ii) characterized the biophysical properties of these hetero-bivalent ligands and their binding properties to IgE antibodies; iii) evaluated the potential of these hetero-bivalent ligands to inhibit allergic responses by using a in vitro basophilic cell assay. The long-term goal of this project is to develop a broadly applicable technology that can selectively inhibit the allergic responses induced by an allergen via competitively inhibiting its binding to the IgE antibodies with engineered hetero-bivalent ligands. In addition, this approach has the potential to discover the utilization of a non-conventional binding site on antibody Fab regions by design of hetero-bivalent ligands.