T Cell Epitope-Containing Domains of Ragweed Amb a 1 and Mugwort Art v 6 Modulate Immunologic Responses in Humans and Mice.

Ana I Sancho,Claudia Asam,Christof Ebner,Fatima Ferreira,Barbara Bohle,Michael Hauser,Martin Himly,Beatrice Jahn-Schmid,Birgit Nagl,Michael Wallner,Takuma Kato

doi:10.1371/journal.pone.0169784

Abstract

BackgroundRagweed (Ambrosia artemisiifolia) and mugwort (Artemisia vulgaris) are the major cause of pollen allergy in late summer. Allergen-specific lymphocytes are crucial for immune modulation during immunotherapy. We sought to generate and pre-clinically characterise highly immunogenic domains of the homologous pectate lyases in ragweed (Amb a 1) and mugwort pollen (Art v 6) for immunotherapy.MethodsDomains of Amb a 1 (Amb a 1α) and Art v 6 (Art v 6α) and a hybrid molecule, consisting of both domains, were designed, expressed in E. coli and purified. Human IgE reactivity and allergenicity were assessed by ELISA and mediator release experiments using ragweed and mugwort allergic patients. Moreover, T cell proliferation was determined. Blocking IgG antibodies and cytokine production in BALB/c mice were studied by ELISA and ELISPOT.ResultsThe IgE binding capacity and in vitro allergenic activity of the Amb a 1 and Art v 6 domains and the hybrid were either greatly reduced or abolished. The recombinant proteins induced T cell proliferative responses comparable to those of the natural allergens, indicative of retained allergen-specific T cell response. Mice immunisation with the hypoallergens induced IL-4, IL-5, IL-13 and IFN-γ production after antigen-specific in vitro re-stimulation of splenocytes. Moreover, murine IgG antibodies that inhibited specific IgE binding of ragweed and mugwort pollen allergic patients were detected.ConclusionAccumulation of T cell epitopes and deletion of IgE reactive areas of Amb a 1 and Art v 6, modulated the immunologic properties of the allergen immuno-domains, leading to promising novel candidates for therapeutic approach.

Highlights

Allergen immunotherapy (AIT) is the only treatment of allergy capable of modulating the inflammatory T cell response, inducing allergen-specific regulatory T cells, and activating B cells to produce allergen-specific IgG blocking antibodies [1,2,3]
Human IgE reactivity and allergenicity were assessed by Enzyme-linked immunosorbent assay (ELISA) and mediator release experiments using ragweed and mugwort allergic patients
To reduce the risk of IgE mediated side effects associated with allergen extracts during AIT [4], recombinant-based formulations containing hypoallergens have been developed as candidates in the treatment of pollen allergy [5]

Summary

Introduction

Allergen immunotherapy (AIT) is the only treatment of allergy capable of modulating the inflammatory T cell response, inducing allergen-specific regulatory T cells, and activating B cells to produce allergen-specific IgG blocking antibodies [1,2,3]. To reduce the risk of IgE mediated side effects associated with allergen extracts during AIT [4], recombinant-based formulations containing hypoallergens have been developed as candidates in the treatment of pollen allergy [5]. In contrast to tree and grass pollen vaccine candidates [5], well-characterised recombinant allergens are not yet available for short ragweed (Ambrosia artemisiifolia), which represents one of the most prominent seasonal allergen sources across the United States, Canada and parts of Europe [6,7]. Mugwort (Artemisia vulgaris) pollen represents the main cause of seasonal IgEmediated allergy in late summer in many areas in Europe and Asia. Ragweed (Ambrosia artemisiifolia) and mugwort (Artemisia vulgaris) are the major cause of pollen allergy in late summer. We sought to generate and pre-clinically characterise highly immunogenic domains of the homologous pectate lyases in ragweed (Amb a 1) and mugwort pollen (Art v 6) for immunotherapy.

Methods

Results

Conclusion