Bee Venom Immunotherapy: Current Status and Future Directions.

Bee venom immunotherapy is the main treatment option for bee sting allergy. Its major limitations are the high percentage of allergic side effects and long duration, which are driving the development of novel therapeutic modalities. Three general approaches have been evaluated including the use of hypoallergenic allergen derivatives, adjunctive therapy, and alternative delivery routes. This article reviews preclinical and clinical evidence on the therapeutic potential of these new therapies. Among hypoallergenic derivatives, hybrid allergens showed a markedly reduced IgE reactivity in mouse models. Whether they will offer therapeutic benefit over extract, it is still not known since clinical trials have not been carried out yet. T cell epitope peptides have proven effective in small clinical trials. Major histocompatibility complex class II restriction was circumvented by using long overlapping or promiscuous T cell epitope peptides. However, the T cell-mediated late-phase adverse events have been reported with both short and longer peptides. Application of mimotopes could potentially overcome both T cell- and IgE-mediated adverse events. During this evolution of vaccine, there has been a gain in safety. The efficacy was further improved with the use of Toll-like receptor-activating adjuvants and delivery systems. In murine models, the association of allergen Api m 1 with cytosine-guanosine rich oligonucleotides stimulated strong T-helper type-1 response, whereas its encapsulation into microbubbles protected mice against allergen challenge. An intralymphatic administration of low-dose vaccine has shown the potential to decrease treatment from 5 years to only 12 weeks. Bigger clinical trials are needed to follow up on these results.

Development and Characterization of Peptide Ligands of Immunoglobulin G Fc Region.

Affinity chromatography based on bacterial immunoglobulin (Ig)-binding proteins represents the cornerstone of therapeutic antibody downstream processing. However, there is a pressing need for more robust affinity ligands that would withstand the harsh column sanitization conditions, while still displaying high selectivity for antibodies. Here, we report the development of linear peptide IgG ligands, identified from combinatorial phage-display library screens. The lead peptide was shown to compete with staphylococcal protein A for the IgG Fc region. Trimming analysis and alanine scanning revealed the minimal structural requirements of the peptide for Fc binding, and the minimized peptide GSYWYQVWF recognized all human IgG subtypes. Mutation of glutamine located at the nonessential position 6 to aspartate led to the optimized peptide GSYWYDVWF with 18-fold higher affinity ( KD app. 0.6 µM) compared to the parent peptide. When coupled to paramagnetic beads or a chromatographic matrix, the optimized ligand was shown to selectively enrich antibodies from complex protein mixtures.

Alternative Affinity Ligands for Immunoglobulins.

The demand for recombinant therapeutic antibodies and Fc-fusion proteins is expected to increase in the years to come. Hence, extensive efforts are concentrated on improving the downstream processing. In particular, the development of better-affinity chromatography matrices, supporting robust time- and cost-effective antibody purification, is warranted. With the advances in molecular design and high-throughput screening approaches from chemical and biological combinatorial libraries, novel affinity ligands representing alternatives to bacterial immunoglobulin (Ig)-binding proteins have entered the scene. Here, we review the design, development, and properties of diverse classes of alternative antibody-binding ligands, ranging from engineered versions of Ig-binding proteins, to artificial binding proteins, peptides, aptamers, and synthetic small-molecular-weight compounds. We also provide examples of applications for the novel affinity matrices in chromatography and beyond.