RESUMO
BACKGROUND: The shrimp Litopenaeus vannamei is an important source of food allergens but its allergenic repertoire is poorly characterized. Cross-reactivity between crustacean and mites has been reported, with tropomyosin, the most relevant allergen involved. The aim of this study was to investigate the structural and immunological properties of a recombinant Fatty Acid Binding Protein (FABP) family from L. vannamei (LvFABP). METHODS: ELISA, skin prick test (SPT) and basophil activation assays were performed to determine IgE reactivity and allergenic activity of LvFABP. LC-MS/MS and Circular Dichroism experiments were done for structural analysis. B-cell epitope mapping with overlapping peptides, and cross-inhibition studies using human sera were done to identify antigenic regions and cross-reactivity. RESULTS: The recombinant LvFABP bound serum IgE from 27% of 36 shrimp allergic patients and showed allergenic activity when tested for basophil activation and SPT in a selected number of them. CD-spectroscopy of LvFABP revealed that the protein is folded with a secondary structure composed of mainly ß-strands and a smaller fraction of α helices. This is consistent with molecular modelling results, which exhibit a typical ß barrel fold with two α-helices and ten ß-strands. Epitope mapping identified two IgE-binding antigenic regions and inhibition assays found high cross-reactivity between LvFABP and Blo t 13, mediated by the antigenic region involving amino acids 54 to 72. CONCLUSIONS: Our results show that LvFABP is a shrimp allergen that cross reacts with the house dust mite allergen Blo t 13 and has allergenic activity, which suggest that it could be clinically relevant in case of shellfish allergy. This new allergen, named Lit v 13, will also help to understand basic mechanisms of sensitization to shrimp.
Assuntos
Hipersensibilidade Alimentar , Penaeidae , Alérgenos , Animais , Cromatografia Líquida , Reações Cruzadas , Proteínas de Ligação a Ácido Graxo , Hipersensibilidade Alimentar/diagnóstico , Humanos , Imunoglobulina E , Espectrometria de Massas em TandemRESUMO
The house dust mite (HDM) Dermatophagoides pteronyssinus is an important risk factor for asthma and rhinitis. Allergen specific immunotherapy that is based on recombinant proteins has been proposed for the safer and more efficient treatment of allergic diseases. The aim of this study was to design and obtain a hybrid protein (DPx4) containing antigenic regions of allergens Der p 1, Der p 2, Der p 7, and Der p 10 from this mite. DPx4 was produced in Escherichia coli and its folding was determined by circular dichroism. Non-denaturing dot-blot, ELISA, basophil activation test, dot blot with monoclonal antibodies, ELISA inhibition, and cysteine protease activity assays were performed. Mice that were immunized with DPx4 were also analyzed. We found that DPx4 had no cysteine protease activity and it showed significantly lower IgE reactivity than Der p 1, Der p 2, and D. pteronyssinus extract. DPx4 induced lower basophil activation than Der p 2 and the allergen extract. Immunized mice produced IgG antibodies that inhibited the binding of allergic patient's IgE to the allergen extract and induced comparatively higher levels of IL-10 than the extract in peripheral blood mononuclear cells (PBMC) culture. These results suggest that DPx4 has immunological properties that are useful for the development of a mite allergy vaccine.
Assuntos
Alérgenos/uso terapêutico , Antígenos de Dermatophagoides/uso terapêutico , Dermatophagoides pteronyssinus/imunologia , Hipersensibilidade/prevenção & controle , Alérgenos/genética , Alérgenos/imunologia , Animais , Antígenos de Dermatophagoides/genética , Antígenos de Dermatophagoides/imunologia , Dermatophagoides pteronyssinus/genética , Feminino , Humanos , Hipersensibilidade/imunologia , Imunização , Camundongos , Camundongos Endogâmicos BALB C , Engenharia de Proteínas , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/uso terapêutico , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologia , Vacinas Sintéticas/uso terapêuticoRESUMO
BACKGROUND: Sensitization to allergens of the house dust mites Dermatophagoides pteronyssinnus and Blomia tropicalis is an important risk factor for asthma and allergic diseases. Allergen-specific immunotherapy is currently based on natural allergen extracts, however, in the last years recombinant allergens with different modifications have shown promising immunological properties that may be advantageously applied for developing novel allergy vaccines. METHODS: A hybrid molecule (MAVAC-BD-2) containing epitopes of B. tropicalis (Blo t 5, Blo t 8 and Blo t 10) and D. pteronyssinus (Der p 1, Der p 2, Der p 7 and Der p 8) allergens was constructed, expressed in Escherichia coli and purified by affinity chromatography. Its folding was analyzed by circular dichroism. Antibody reactivities were evaluated by ELISA and non-denaturing dot blot assays using a battery of sera from mite allergic patients and non-allergic subjects. ELISA inhibition and dot blot assays with monoclonal antibodies were used to detect B-cell epitopes. Human basophil activation and induction of IgG-blocking antibodies in mice immunized with the hybrid protein were also evaluated. RESULTS: MAVAC-BD-2, expressed as a 22.8â¯kDa protein, showed a lower frequency and strength of IgE reactivity compared to Blo t 5, Der p 1, Der p 2 and the extracts of B. tropicalis and D. pteronyssinus. MAVAC-BD-2 inhibited 26% of IgE reactivity to Der p 2 and Blo t 5, reacted with anti-Der p 1 and anti-Der p 2 monoclonal antibodies and did not induce relevant basophil activation. MAVAC-BD-2 immunized mice produced specific antibodies that reacted against mite extracts and the purified allergens, as well as IgG antibodies that blocked the human IgE reactivity to mite extracts. CONCLUSION: MAVAC-BD-2 has hypoallergenic characteristics and in mice induces IgG antibodies that block the human IgE reactivity to mite extracts.
Assuntos
Alérgenos/imunologia , Proteínas de Artrópodes/imunologia , Dermatophagoides pteronyssinus/imunologia , Ácaros/imunologia , Proteínas Recombinantes de Fusão/imunologia , Alérgenos/genética , Alérgenos/metabolismo , Animais , Antígenos de Dermatophagoides/genética , Antígenos de Dermatophagoides/imunologia , Antígenos de Dermatophagoides/metabolismo , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismo , Reações Cruzadas/imunologia , Dermatophagoides pteronyssinus/genética , Dermatophagoides pteronyssinus/metabolismo , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunização , Imunoglobulina E/imunologia , Masculino , Camundongos Endogâmicos BALB C , Ácaros/genética , Ácaros/metabolismo , Engenharia de Proteínas/métodos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
In a survey of plants from Ecuador with antiprotozoal activity, Cupania cinerea was found to show significant in vitro activity against the Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense. Subsequently, activity-guided isolation of the n-hexane and dichloromethane extracts from the bark of C. cinerea afforded two diterpene glycosides (1 and 2), named cupacinoside and 6'-de-O-acetylcupacinoside, and a lactonized triterpene bearing an oxepin moiety named cupacinoxepin (3), together with the known compounds scopoletin (4), caryophyllene oxide (5), two bisabolane sesquiterpenes (6 and 7), lichexanthone (8), gustastatin (9), lupenone (10), betulone (11), 17ß,21ß-epoxyhopan-3-one (12), taraxerol (13), and taraxerone (14). For compound 3, X-ray crystallography was employed to elucidate the relative configuration. For cupacinosides (1) and (2) and cupacinoxepin (3), in vitro activities against the P. falciparum K1 strain (IC(50)1, 1.3; 2, 1.8; and 3, 8.7 µM) and T. b. rhodesiense (IC(50)1, 4.5; 2, 15.8; and 3, 71.6 µM) were found. Cytotoxicity toward L-6 cells is discussed for all the compounds isolated.