A hybrid of two major Blomia tropicalis allergens as an allergy vaccine candidate

Abstract

Introduction Allergen‐specific immunotherapy (AIT) represents a curative approach for treating allergies. In the tropical and subtropical regions of the world, Blomia tropicalis (Blo t 5 and Blo t 21) is the likely dominant source of indoor allergens. Aim To generate a hypoallergenic Blo t 5/Blo t 21 hybrid molecule that can treat allergies caused by B tropicalis . Methods Using in silico design of B tropicalis hybrid proteins, we chose two hybrid proteins for heterologous expression. Wild‐type Blo t 5/Blo t 21 hybrid molecule and a hypoallergenic version, termed BTH1 and BTH2, respectively, were purified by ion exchange and size exclusion chromatography and characterized by physicochemical, as well as in vitro and in vivo immunological, experiments. Results BTH1, BTH2 and the parental allergens were purified to homogeneity and characterized in detail. BTH2 displayed the lowest IgE reactivity that induced basophil degranulation using sera from allergic rhinitis and asthmatic patients. BTH2 essentially presented the same endolysosomal degradation pattern as the shortened rBlo t 5 and showed a higher resistance towards degradation than the full‐length Blo t 5. In vivo immunization of mice with BTH2 led to the production of IgG antibodies that competed with human IgE for allergen binding. Stimulation of splenocytes from BTH2‐immunized mice produced higher levels of IL‐10 and decreased secretion of IL‐4 and IL‐5. In addition, BTH2 stimulated T‐cell proliferation in PBMCs isolated from allergic patients, with secretion of higher levels of IL‐10 and lower levels of IL‐5 and IL‐13, when compared to parental allergens. Conclusions and Clinical Relevance BTH2 is a promising hybrid vaccine candidate for immunotherapy of Blomia allergy. However, further pre‐clinical studies addressing its efficacy and safety are needed.

Abundance and Stability as Common Properties of Allergens

“…For example, stabilized N-terminal truncations of the mite allergen Blo t 5 have been shown to enhance IL-10 production and suppress IL-4, skewing the immune system toward a modified Th2 response ( 98 ). Building upon this approach, a hybrid Blo t 5/Blo t 21 molecule has been developed as a potential allergy therapeutic ( 150 ). Here, the authors were able to retain the same endosomal degradation patterns while reducing IgE binding to the intact protein ( 98 , 150 ).…”

“…Building upon this approach, a hybrid Blo t 5/Blo t 21 molecule has been developed as a potential allergy therapeutic ( 150 ). Here, the authors were able to retain the same endosomal degradation patterns while reducing IgE binding to the intact protein ( 98 , 150 ). The enhanced stability of the hybrid molecule ensured that these resulting endosomal fragments yielded a protective response against their wild-type counterparts.…”

Allergen Immunotherapy: Current and Future Trends

“…This protein reduced IgE to Blot 5 and Der p 2 by 20%, approximately, while boosting IgG. Concerning the limits of these products, it is probable that the addition of aggregates could impact protein stability [ 140 , 141 , 142 ]. The clinical-immune efficacy of some recombinants is better when they are integrated with adjuvants such as MPL or aluminum.…”

Recombinant T‐cell epitope conjugation: A new approach for Dermatophagoides hypoallergen design

“…Peripheral blood from allergic (N = 6) and non-allergic (N = 6) patients was used to obtain PBMC. 23 Cells were stimulated for 120 h with 20 μg/ml of DpE, 12.5 μg/ml of rDer p 2231; 10 μg/ml of pokeweed mitogen (PWM) was used as a positive control. [23][24][25][26][27] Supernatants were used to quantify a total of 18 cytokines, which were detected simultaneously using a multiplex human cytokine/ chemokine magnetic bead panel (MILLIPLEX MAP Human Cytokine/ Chemokine Magnetic Bead Panel -Immunology Multiplex Assay, Millipore), following the manufacturer's instructions.…”