A Novel Approach to Specific Allergy Treatment: The Recombinant Fusion Protein of a Bacterial Cell Surface (S-Layer) Protein and the Major Birch Pollen Allergen Bet v 1 (rSbsC-Bet v 1) Combines Reduced Allergenicity with Immunomodulating Capacity

Abstract

Counterregulating the disease-eliciting Th2-like immune response of allergen-specific Th lymphocytes by fostering an allergen-specific Th1-like response is a promising concept for future immunotherapy of type I allergy. The use of recombinant allergens combined with more functional adjuvants has been proposed. In this respect, we present a novel approach. The gene sequence encoding the major birch pollen allergen, Bet v 1, was fused with the gene encoding the bacterial cell surface (S-layer) protein of Geobacillus stearothermophilus, resulting in the recombinant protein, rSbsC-Bet v 1. rSbsC-Bet v 1 contained all relevant Bet v 1-specific B and T cell epitopes, but was significantly less efficient to release histamine than rBet v 1. In cells of birch pollen-allergic individuals, rSbsC-Bet v 1 induced IFN-γ along with IL-10, but no Th2-like response, as observed after stimulation with Bet v 1. Intracellular cytokine staining revealed that rSbsC-Bet v 1 promoted IFN-γ-producing Th cells. Moreover, rSbsC-Bet v 1 induced IFN-γ synthesis in Bet v 1-specific Th2 cell clones, and importantly, increased IL-10 production in these cells. In conclusion, genetic fusion of an allergen to S-layer proteins combined reduced allergenicity with immunomodulatory capacity. The strategy described in this work may be generally applied to design vaccines for specific immunotherapy of type I allergy with improved efficacy and safety.

Developments in allergen‐specific immunotherapy: from allergen extracts to allergy vaccines bypassing allergen‐specific immunoglobulin E and T cell reactivity

“…Fusion proteins obtained by this approach showed reduced allergenic activity and an increase in allergen-specific Th1 cell responses [99,100]. Immunotherapy with a conjugate of the major ragweed pollen allergen, Amb a 1, and an immunostimulatory oligonucleotide resulted in a decrease in chest symptoms and a reduction in nasal symptoms [101].…”

“…With the aim of reducing the allergenicity and enhancing the immunogenicity of allergen vaccines, the approach of conjugating allergens to immunostimulatory sequences, either DNA oligonucleotides containing CpG motifs [99] or genes encoding bacterial cell surface proteins, has also been proposed for SIT [100]. Fusion proteins obtained by this approach showed reduced allergenic activity and an increase in allergen-specific Th1 cell responses [99,100].…”

Birch Pollen-Related Food Allergy: An Excellent Disease Model to Understand the Relevance of Immunological Cross-Reactivity for Allergy

“…variants with reduced IgE-binding capacity, multi-mers of single allergens or hybrids consisting of different allergens. Furthermore, allergens can be genetically fused with proteins that promote immune responses which counter regulate the disease-eliciting Th2-dominated immune response in allergic individuals and may therefore, improve the efficacy of SIT (Bohle et al, 2004. All these approaches may also be employed to develop an effective treatment strategy for birch pollen-related food allergy.…”

A Novel Approach to Specific Allergy Treatment: The Recombinant Allergen-S-Layer Fusion Protein rSbsC-Bet v 1 Matures Dendritic Cells That Prime Th0/Th1 and IL-10-Producing Regulatory T Cells

“…The resulting allergen-S-layer fusion protein rSbsC-Bet v 1 induced IFN-␥ and IL-10 production in PBMC and Bet v 1-specific Th2 clones from birch pollen-allergic donors (31). Moreover, rSbsC-Bet v 1 displayed a reduced IgE-binding capacity, and consequently a lower risk to induce adverse vaccine-related anaphylactic reactions (31). Thus, we consider rSbsC-Bet v 1 as promising hypoallergenic molecule to skew allergen-specific Th2 effector cells to both IFN-␥ and IL-10 production.…”

“…We have proposed to engineer allergy vaccines by genetic fusion of allergens with S-layer proteins: the major birch pollen allergen Bet v 1 was fused with the S-layer protein from the nonpathogenic bacteria Geobacillus stearothermophilus ATCC 12980 (30,31). The resulting allergen-S-layer fusion protein rSbsC-Bet v 1 induced IFN-␥ and IL-10 production in PBMC and Bet v 1-specific Th2 clones from birch pollen-allergic donors (31). Moreover, rSbsC-Bet v 1 displayed a reduced IgE-binding capacity, and consequently a lower risk to induce adverse vaccine-related anaphylactic reactions (31).…”