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Interaction of bee venom with giant unilamellar liposomes

Grant number: 08/00593-3
Support type:Scholarships abroad - Research
Effective date (Start): October 07, 2008
Effective date (End): October 22, 2008
Field of knowledge:Biological Sciences - Biophysics
Principal Investigator:Maria Helena Bueno da Costa
Grantee:Maria Helena Bueno da Costa
Host: Felix M. Goni
Home Institution: Instituto Butantan. Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
Local de pesquisa : Universidad del País Vasco (UPV), Spain  

Abstract

Arthropod bites and stings are capable of inflicting injury, inciting allergic reactions, and transmitting systemic disease. Stings from bees, wasps, and ants produce a variety of clinical and histological manifestations. Anaphylaxis following an insect sting is the most serious complication. For individuals with a specific allergy to Hymenoptera venom, the venom immunotherapy (VIT) may be a relatively effective treatment option. Treatments failures do however occur and VIT may cause frequent systemic allergic side effects, mainly in honeybee venom allergy persons. The Immunotherapy is expensive and time consuming. New strategies to improve safety and efficacy of this treatment are therefore of general interest. We have been developed (FAPESP process number 2005/04514-2) a systematic approach to study the basic and biotechnological problems related with the development of safe formulations of bee venoms within liposomes to be used in VIT. We started studying the mainly molecular characteristics related to mellitin/or BV (whole bee venom) /lipid interactions. It is known, that mellitin (Mel) is the major toxic peptide in the European honey bee venom (50 % of the wet weight) and that it has a powerful hemolytic activity and it is responsible for local pain. The biotechnological challenges were chemically modify the BV or Mel molecule to permit their (Mel or BV) encapsulation within liposomes of natural phospholipids. The chemical modifications were done because both Mel and BV disrupt liposomal membrane integrity. The Mel or BV biological toxicity decreased by two reasons: 1. Because the Mel molecule or BV lost their hemolytic activity through chemical modification and 2. The liposomal encapsulation avoided direct contact between Mel or BV and the organism and, in addition, this vehicle has adjuvant characteristics. The final objective of this project was the development of a stable and smart formulation, able to diminish both, venom quantity and the number of injections used in VIT. Naturally that these studies have been used physical-chemical methods for protein and lipid studies to describe a liposomal system as a stable formulation. Here, the aim of the study is to detail (through confocal microscopy) the interaction between Mel or BV chemically modified with GUVs (Giant Unilamellar vesicles) of different compositions. With the results, we could describe mechanistically the reasons to propose a determinate formulation of Mel or BV encapsulated within liposomes composed of natural phospholipids. (AU)