The hybrid protein BTH2 suppresses allergic airway inflammation in a murine model of HDM-specific immunotherapy

BACKGROUND

Allergen-specific immunotherapy (AIT) is the only disease-modifying treatment approach to change disease-causing allergens. Hypoallergenic derivatives show promise as potential therapeutics, amongst which BTH2 was designed to induce tolerance against Blomia tropicalis allergy. Our aim was to investigate the hypoallergenicity and immunoregulatory activity of BTH2 in vitro and its therapeutic potential in a mouse model of AIT.

METHODS

Recombinant Blo t 5 and Blo t 21 allergens and their hybrid derivatives (BTH1 and BTH2) were expressed and purified. IgE binding capacity was tested by ELISA using sera from Brazilian, Colombian, and Ecuadorian subjects. Secretion of cytokines in supernatants from human cell cultures was measured following stimulation with the four recombinants and controls. The capacity of BTH2 to ameliorate allergic airway inflammation induced by B. tropicalis extract was evaluated in a murine model of AIT.

RESULTS

rBlo t 5 and rBlo t 21 were identified as major allergens in Latin American patients, and BTH2 had the lowest IgE binding. In vitro stimulation of human cells induced greater levels of IL-10 and IFN-γ and reduced the secretion of Th2 cytokines. BTH2 ameliorated allergic airway inflammation in B. tropicalis-challenged A/J mice, as evidenced by the histopathological and humoral biomarkers: decreased Th2 cytokines and cellular infiltration (especially eosinophils), lower activity of eosinophil peroxidase, an increase in IgG blocking antibodies and strong reduction of mucus production by goblet cells.

CONCLUSIONS

Our study shows that BTH2 represents a promising candidate for the treatment of B. tropicalis allergy with hypoallergenic, immune regulatory and therapeutic properties. Further pre-clinical studies are required in murine models of chronic asthma to further address the efficacy and safety of BTH2 as a vaccine against B. tropicalis-induced allergy.

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

BACKGROUND

Allergen-specific immunotherapy (AIT) is the only clinical approach that can potentially cure some allergic diseases by inducing immunological tolerance. Dermatophagoides pteronyssinus is considered as the most important source of mite allergens worldwide, with high sensitization rates for the major allergens Der p 1, Der p 2 and Der p 23. The aim of this work is to generate a hypoallergenic hybrid molecule containing T-cell epitopes from these three major allergens.

METHODS

The hybrid protein termed Der p 2231 containing T-cell epitopes was purified by affinity chromatography. The human IgE reactivity was verified by comparing those with the parental allergens. The hybrid was also characterized immunologically through an in vivo mice model.

RESULTS

The hybrid rDer p 2231 stimulated in peripheral blood mononuclear cells (PBMCs) isolated from allergic patients with higher levels of IL- 2, IL-10, IL-15 and IFN-γ, as well as lower levels of IL-4, IL-5, IL-13, TNF-α and GM-CSF. The use of hybrid molecules as a therapeutic model in D. pteronyssinus allergic mice led to the reduction of IgE production and lower eosinophilic peroxidase activity in the airways. We found increased levels of IgG antibodies that blocked the IgE binding to the parental allergens in the serum of allergic patients. Furthermore, the stimulation of splenocytes from mice treated with rDer p 2231 induced higher levels of IL-10 and IFN-γ and decreased the secretion of IL-4 and IL-5, when compared with parental allergens and D. pteronyssinus extract.

CONCLUSIONS

rDer p 2231 has the potential to be used in AIT in patients co-sensitized with D. pteronyssinus major allergens, once it was able to reduce IgE production, inducing allergen-specific blocking antibodies, restoring and balancing Th1/Th2 immune responses, and inducing regulatory T-cells.

Proteomics and immunoblotting analyses reveal antigens that optimize the immunodiagnosis of the infection by Toxocara spp

BACKGROUND

Toxocariasis is an infection caused by the round worms Toxocara canis and Toxocara cati. It occurs worldwide though it is more prevalent in developing countries. For the diagnosis of toxocariasis, the most used method is the indirect enzyme-linked immunosorbent assay (indirect ELISA), based on the detection of specific antibodies using the excreted/secreted products from T. canis larvae (TES) as antigens, but it cross-reacts with several helminth infections. For this reason, there is a need to investigate species-specific immunoreactive proteins, which can be used for the development of a more sensitive and specific diagnosis.

OBJECTIVE

To investigate immunoreactive protein candidates to be used for the development of a more sensitive and specific diagnosis of Toxocara spp. infection in humans.

METHODS

We have used immunoblotting and mass spectrometry to select four Toxocara canis immunoreactive proteins that were recombinantly expressed in bacteria and evaluated as potential new diagnostic antigens (rMUC3, rTES 26, rTES32 and rCTL4). The recognition of these recombinant proteins by total serum IgG and IgG4 was assayed using the purified proteins in an isolated manner or in combination.

RESULTS

The IgG ELISAs performed with individual recombinant antigens reached values of sensitivity and specificity that ranged from 91.7% to 97.3% and 94.0% to 97.9%, respectively. Among the analyses, the IgG4 immunoassay was proven to be more effective, revealing a sensitivity that ranged from 88.8% to 98.3% and a specificity of 97.8% to 97.9%. The IgG4 ELISA was shown to be more effective and presented no cross-reactivity when using combinations of the rTES 26 and rCTL4 recombinant proteins. The combination of these two molecules achieved 100% sensitivity and specificity.

CONCLUSIONS

The use of only two recombinant proteins can contribute to improve the current panorama of toxocariasis immunodiagnosis for, with a better optimization and reduced cost. This article is protected by copyright. All rights reserved.

Topography and architecture of visual and somatosensory areas of the agouti

We analyzed the organization of the somatosensory and visual cortices of the agouti, a diurnal rodent with a relatively big brain, using a combination of multiunit microelectrode recordings and histological techniques including myelin and cytochrome oxidase staining. We found multiple representations of the sensory periphery in the parietal, temporal, and occipital lobes. While the agouti's primary (V1) and secondary visual areas seemed to lack any obvious modular arrangement, such as blobs or stripes, which are found in some primates and carnivores, the primary somatosensory area (S1) was internally subdivided in discrete regions, isomorphically associated with peripheral structures. Our results confirm and extend previous reports on this species, and provide additional data to understand how variations in lifestyle can influence brain organization in rodents.

Callosal axon arbors in the limb representations of the somatosensory cortex (SI) in the agouti (Dasyprocta primnolopha)

The present report compares the morphology of callosal axon arbors projecting from and to the hind- or forelimb representations in the primary somatosensory cortex (SI) of the agouti (Dasyprocta primnolopha), a large, lisencephlic Brazilian rodent that uses forelimb coordination for feeding. Callosal axons were labeled after single pressure (n = 6) or iontophoretic injections (n = 2) of the neuronal tracer biotinylated dextran amine (BDA, 10 kD), either into the hind- (n = 4) or forelimb (n = 4) representations of SI, as identified by electrophysiological recording. Sixty-nine labeled axon fragments located across all layers of contralateral SI representations of the hindlimb (n = 35) and forelimb (n = 34) were analyzed. Quantitative morphometric features such as densities of branching points and boutons, segments length, branching angles, and terminal field areas were measured. Cluster analysis of these values revealed the existence of two types of axon terminals: Type I (46.4%), less branched and more widespread, and Type II (53.6%), more branched and compact. Both axon types were asymmetrically distributed; Type I axonal fragments being more frequent in hindlimb (71.9%) vs. forelimb (28.13%) representation, while most of Type II axonal arbors were found in the forelimb representation (67.56%). We concluded that the sets of callosal axon connecting fore- and hindlimb regions in SI are morphometrically distinct from each other. As callosal projections in somatosensory and motor cortices seem to be essential for bimanual interaction, we suggest that the morphological specialization of callosal axons in SI of the agouti may be correlated with this particular function.